uglify-es

JavaScript parser, mangler/compressor and beautifier toolkit for ES6+
uglify uglify-es uglify-js minify minifier javascript ecmascript es5 es6 es7 es8 es2015 es2016 es2017 async await


Summary

Project Name uglify-es Project Url https://github.com/mishoo/UglifyJS2/tree/harmony
InceptionYear 2017-05-09 19:18:47 更新时间 2018-01-28 00:54:24
IssueManagement https://github.com/mishoo/UglifyJS2/issues Licenses BSD-2-Clause
仓库地址 git+https://github.com/mishoo/UglifyJS2.git#harmony 用户数 28
Node Engine >=0.8.0 文件大小 153.1 KB
install test

项目介绍

uglify-es ========= A JavaScript parser, mangler/compressor and beautifier toolkit for ES6+. #### Note: - **`uglify-es` is API/CLI compatible with `uglify-js@3`.** - **`uglify-es` is not backwards compatible with `uglify-js@2`.** Install ------- First make sure you have installed the latest version of [node.js](http://nodejs.org/) (You may need to restart your computer after this step). From NPM for use as a command line app: npm install uglify-es -g From NPM for programmatic use: npm install uglify-es # Command line usage uglifyjs [input files] [options] UglifyJS can take multiple input files. It's recommended that you pass the input files first, then pass the options. UglifyJS will parse input files in sequence and apply any compression options. The files are parsed in the same global scope, that is, a reference from a file to some variable/function declared in another file will be matched properly. If no input file is specified, UglifyJS will read from STDIN. If you wish to pass your options before the input files, separate the two with a double dash to prevent input files being used as option arguments: uglifyjs --compress --mangle -- input.js ### Command line options ``` -h, --help Print usage information. `--help options` for details on available options. -V, --version Print version number. -p, --parse Specify parser options: `acorn` Use Acorn for parsing. `bare_returns` Allow return outside of functions. Useful when minifying CommonJS modules and Userscripts that may be anonymous function wrapped (IIFE) by the .user.js engine `caller`. `expression` Parse a single expression, rather than a program (for parsing JSON). `spidermonkey` Assume input files are SpiderMonkey AST format (as JSON). -c, --compress [options] Enable compressor/specify compressor options: `pure_funcs` List of functions that can be safely removed when their return values are not used. -m, --mangle [options] Mangle names/specify mangler options: `reserved` List of names that should not be mangled. --mangle-props [options] Mangle properties/specify mangler options: `builtins` Mangle property names that overlaps with standard JavaScript globals. `debug` Add debug prefix and suffix. `domprops` Mangle property names that overlaps with DOM properties. `keep_quoted` Only mangle unquoted properties. `regex` Only mangle matched property names. `reserved` List of names that should not be mangled. -b, --beautify [options] Beautify output/specify output options: `beautify` Enabled with `--beautify` by default. `preamble` Preamble to prepend to the output. You can use this to insert a comment, for example for licensing information. This will not be parsed, but the source map will adjust for its presence. `quote_style` Quote style: 0 - auto 1 - single 2 - double 3 - original `wrap_iife` Wrap IIFEs in parenthesis. Note: you may want to disable `negate_iife` under compressor options. -o, --output Output file path (default STDOUT). Specify `ast` or `spidermonkey` to write UglifyJS or SpiderMonkey AST as JSON to STDOUT respectively. --comments [filter] Preserve copyright comments in the output. By default this works like Google Closure, keeping JSDoc-style comments that contain "@license" or "@preserve". You can optionally pass one of the following arguments to this flag: - "all" to keep all comments - a valid JS RegExp like `/foo/` or `/^!/` to keep only matching comments. Note that currently not *all* comments can be kept when compression is on, because of dead code removal or cascading statements into sequences. --config-file Read `minify()` options from JSON file. -d, --define [=value] Global definitions. --ecma Specify ECMAScript release: 5, 6, 7 or 8. --ie8 Support non-standard Internet Explorer 8. Equivalent to setting `ie8: true` in `minify()` for `compress`, `mangle` and `output` options. By default UglifyJS will not try to be IE-proof. --keep-classnames Do not mangle/drop class names. --keep-fnames Do not mangle/drop function names. Useful for code relying on Function.prototype.name. --name-cache File to hold mangled name mappings. --safari10 Support non-standard Safari 10/11. Equivalent to setting `safari10: true` in `minify()` for `mangle` and `output` options. By default `uglify-es` will not work around Safari 10/11 bugs. --self Build UglifyJS as a library (implies --wrap UglifyJS) --source-map [options] Enable source map/specify source map options: `base` Path to compute relative paths from input files. `content` Input source map, useful if you're compressing JS that was generated from some other original code. Specify "inline" if the source map is included within the sources. `filename` Name and/or location of the output source. `includeSources` Pass this flag if you want to include the content of source files in the source map as sourcesContent property. `root` Path to the original source to be included in the source map. `url` If specified, path to the source map to append in `//# sourceMappingURL`. --timings Display operations run time on STDERR. --toplevel Compress and/or mangle variables in top level scope. --verbose Print diagnostic messages. --warn Print warning messages. --wrap Embed everything in a big function, making the “exports” and “global” variables available. You need to pass an argument to this option to specify the name that your module will take when included in, say, a browser. ``` Specify `--output` (`-o`) to declare the output file. Otherwise the output goes to STDOUT. ## CLI source map options UglifyJS can generate a source map file, which is highly useful for debugging your compressed JavaScript. To get a source map, pass `--source-map --output output.js` (source map will be written out to `output.js.map`). Additional options: - `--source-map "filename=''"` to specify the name of the source map. - `--source-map "root=''"` to pass the URL where the original files can be found. - `--source-map "url=''"` to specify the URL where the source map can be found. Otherwise UglifyJS assumes HTTP `X-SourceMap` is being used and will omit the `//# sourceMappingURL=` directive. For example: uglifyjs js/file1.js js/file2.js \ -o foo.min.js -c -m \ --source-map "root='http://foo.com/src',url='foo.min.js.map'" The above will compress and mangle `file1.js` and `file2.js`, will drop the output in `foo.min.js` and the source map in `foo.min.js.map`. The source mapping will refer to `http://foo.com/src/js/file1.js` and `http://foo.com/src/js/file2.js` (in fact it will list `http://foo.com/src` as the source map root, and the original files as `js/file1.js` and `js/file2.js`). ### Composed source map When you're compressing JS code that was output by a compiler such as CoffeeScript, mapping to the JS code won't be too helpful. Instead, you'd like to map back to the original code (i.e. CoffeeScript). UglifyJS has an option to take an input source map. Assuming you have a mapping from CoffeeScript → compiled JS, UglifyJS can generate a map from CoffeeScript → compressed JS by mapping every token in the compiled JS to its original location. To use this feature pass `--source-map "content='/path/to/input/source.map'"` or `--source-map "content=inline"` if the source map is included inline with the sources. ## CLI compress options You need to pass `--compress` (`-c`) to enable the compressor. Optionally you can pass a comma-separated list of [compress options](#compress-options). Options are in the form `foo=bar`, or just `foo` (the latter implies a boolean option that you want to set `true`; it's effectively a shortcut for `foo=true`). Example: uglifyjs file.js -c toplevel,sequences=false ## CLI mangle options To enable the mangler you need to pass `--mangle` (`-m`). The following (comma-separated) options are supported: - `toplevel` (default `false`) -- mangle names declared in the top level scope. - `eval` (default `false`) -- mangle names visible in scopes where `eval` or `with` are used. When mangling is enabled but you want to prevent certain names from being mangled, you can declare those names with `--mangle reserved` — pass a comma-separated list of names. For example: uglifyjs ... -m reserved=['$','require','exports'] to prevent the `require`, `exports` and `$` names from being changed. ### CLI mangling property names (`--mangle-props`) **Note:** THIS WILL PROBABLY BREAK YOUR CODE. Mangling property names is a separate step, different from variable name mangling. Pass `--mangle-props` to enable it. It will mangle all properties in the input code with the exception of built in DOM properties and properties in core JavaScript classes. For example: ```javascript // example.js var x = { baz_: 0, foo_: 1, calc: function() { return this.foo_ + this.baz_; } }; x.bar_ = 2; x["baz_"] = 3; console.log(x.calc()); ``` Mangle all properties (except for JavaScript `builtins`): ```bash $ uglifyjs example.js -c -m --mangle-props ``` ```javascript var x={o:0,_:1,l:function(){return this._+this.o}};x.t=2,x.o=3,console.log(x.l()); ``` Mangle all properties except for `reserved` properties: ```bash $ uglifyjs example.js -c -m --mangle-props reserved=[foo_,bar_] ``` ```javascript var x={o:0,foo_:1,_:function(){return this.foo_+this.o}};x.bar_=2,x.o=3,console.log(x._()); ``` Mangle all properties matching a `regex`: ```bash $ uglifyjs example.js -c -m --mangle-props regex=/_$/ ``` ```javascript var x={o:0,_:1,calc:function(){return this._+this.o}};x.l=2,x.o=3,console.log(x.calc()); ``` Combining mangle properties options: ```bash $ uglifyjs example.js -c -m --mangle-props regex=/_$/,reserved=[bar_] ``` ```javascript var x={o:0,_:1,calc:function(){return this._+this.o}};x.bar_=2,x.o=3,console.log(x.calc()); ``` In order for this to be of any use, we avoid mangling standard JS names by default (`--mangle-props builtins` to override). A default exclusion file is provided in `tools/domprops.json` which should cover most standard JS and DOM properties defined in various browsers. Pass `--mangle-props domprops` to disable this feature. A regular expression can be used to define which property names should be mangled. For example, `--mangle-props regex=/^_/` will only mangle property names that start with an underscore. When you compress multiple files using this option, in order for them to work together in the end we need to ensure somehow that one property gets mangled to the same name in all of them. For this, pass `--name-cache filename.json` and UglifyJS will maintain these mappings in a file which can then be reused. It should be initially empty. Example: ```bash $ rm -f /tmp/cache.json # start fresh $ uglifyjs file1.js file2.js --mangle-props --name-cache /tmp/cache.json -o part1.js $ uglifyjs file3.js file4.js --mangle-props --name-cache /tmp/cache.json -o part2.js ``` Now, `part1.js` and `part2.js` will be consistent with each other in terms of mangled property names. Using the name cache is not necessary if you compress all your files in a single call to UglifyJS. ### Mangling unquoted names (`--mangle-props keep_quoted`) Using quoted property name (`o["foo"]`) reserves the property name (`foo`) so that it is not mangled throughout the entire script even when used in an unquoted style (`o.foo`). Example: ```javascript // stuff.js var o = { "foo": 1, bar: 3 }; o.foo += o.bar; console.log(o.foo); ``` ```bash $ uglifyjs stuff.js --mangle-props keep_quoted -c -m ``` ```javascript var o={foo:1,o:3};o.foo+=o.o,console.log(o.foo); ``` ### Debugging property name mangling You can also pass `--mangle-props debug` in order to mangle property names without completely obscuring them. For example the property `o.foo` would mangle to `o._$foo$_` with this option. This allows property mangling of a large codebase while still being able to debug the code and identify where mangling is breaking things. ```bash $ uglifyjs stuff.js --mangle-props debug -c -m ``` ```javascript var o={_$foo$_:1,_$bar$_:3};o._$foo$_+=o._$bar$_,console.log(o._$foo$_); ``` You can also pass a custom suffix using `--mangle-props debug=XYZ`. This would then mangle `o.foo` to `o._$foo$XYZ_`. You can change this each time you compile a script to identify how a property got mangled. One technique is to pass a random number on every compile to simulate mangling changing with different inputs (e.g. as you update the input script with new properties), and to help identify mistakes like writing mangled keys to storage. # API Reference Assuming installation via NPM, you can load UglifyJS in your application like this: ```javascript var UglifyJS = require("uglify-es"); ``` There is a single high level function, **`minify(code, options)`**, which will perform all minification [phases](#minify-options) in a configurable manner. By default `minify()` will enable the options [`compress`](#compress-options) and [`mangle`](#mangle-options). Example: ```javascript var code = "function add(first, second) { return first + second; }"; var result = UglifyJS.minify(code); console.log(result.error); // runtime error, or `undefined` if no error console.log(result.code); // minified output: function add(n,d){return n+d} ``` You can `minify` more than one JavaScript file at a time by using an object for the first argument where the keys are file names and the values are source code: ```javascript var code = { "file1.js": "function add(first, second) { return first + second; }", "file2.js": "console.log(add(1 + 2, 3 + 4));" }; var result = UglifyJS.minify(code); console.log(result.code); // function add(d,n){return d+n}console.log(add(3,7)); ``` The `toplevel` option: ```javascript var code = { "file1.js": "function add(first, second) { return first + second; }", "file2.js": "console.log(add(1 + 2, 3 + 4));" }; var options = { toplevel: true }; var result = UglifyJS.minify(code, options); console.log(result.code); // console.log(3+7); ``` The `nameCache` option: ```javascript var options = { mangle: { toplevel: true, }, nameCache: {} }; var result1 = UglifyJS.minify({ "file1.js": "function add(first, second) { return first + second; }" }, options); var result2 = UglifyJS.minify({ "file2.js": "console.log(add(1 + 2, 3 + 4));" }, options); console.log(result1.code); // function n(n,r){return n+r} console.log(result2.code); // console.log(n(3,7)); ``` You may persist the name cache to the file system in the following way: ```javascript var cacheFileName = "/tmp/cache.json"; var options = { mangle: { properties: true, }, nameCache: JSON.parse(fs.readFileSync(cacheFileName, "utf8")) }; fs.writeFileSync("part1.js", UglifyJS.minify({ "file1.js": fs.readFileSync("file1.js", "utf8"), "file2.js": fs.readFileSync("file2.js", "utf8") }, options).code, "utf8"); fs.writeFileSync("part2.js", UglifyJS.minify({ "file3.js": fs.readFileSync("file3.js", "utf8"), "file4.js": fs.readFileSync("file4.js", "utf8") }, options).code, "utf8"); fs.writeFileSync(cacheFileName, JSON.stringify(options.nameCache), "utf8"); ``` An example of a combination of `minify()` options: ```javascript var code = { "file1.js": "function add(first, second) { return first + second; }", "file2.js": "console.log(add(1 + 2, 3 + 4));" }; var options = { toplevel: true, compress: { global_defs: { "@console.log": "alert" }, passes: 2 }, output: { beautify: false, preamble: "/* uglified */" } }; var result = UglifyJS.minify(code, options); console.log(result.code); // /* uglified */ // alert(10);" ``` To produce warnings: ```javascript var code = "function f(){ var u; return 2 + 3; }"; var options = { warnings: true }; var result = UglifyJS.minify(code, options); console.log(result.error); // runtime error, `undefined` in this case console.log(result.warnings); // [ 'Dropping unused variable u [0:1,18]' ] console.log(result.code); // function f(){return 5} ``` An error example: ```javascript var result = UglifyJS.minify({"foo.js" : "if (0) else console.log(1);"}); console.log(JSON.stringify(result.error)); // {"message":"Unexpected token: keyword (else)","filename":"foo.js","line":1,"col":7,"pos":7} ``` Note: unlike `uglify-js@2.x`, the `3.x` API does not throw errors. To achieve a similar effect one could do the following: ```javascript var result = UglifyJS.minify(code, options); if (result.error) throw result.error; ``` ## Minify options - `ecma` (default `undefined`) - pass `5`, `6`, `7` or `8` to override `parse`, `compress` and `output` options. - `warnings` (default `false`) — pass `true` to return compressor warnings in `result.warnings`. Use the value `"verbose"` for more detailed warnings. - `parse` (default `{}`) — pass an object if you wish to specify some additional [parse options](#parse-options). - `compress` (default `{}`) — pass `false` to skip compressing entirely. Pass an object to specify custom [compress options](#compress-options). - `mangle` (default `true`) — pass `false` to skip mangling names, or pass an object to specify [mangle options](#mangle-options) (see below). - `mangle.properties` (default `false`) — a subcategory of the mangle option. Pass an object to specify custom [mangle property options](#mangle-properties-options). - `output` (default `null`) — pass an object if you wish to specify additional [output options](#output-options). The defaults are optimized for best compression. - `sourceMap` (default `false`) - pass an object if you wish to specify [source map options](#source-map-options). - `toplevel` (default `false`) - set to `true` if you wish to enable top level variable and function name mangling and to drop unused variables and functions. - `nameCache` (default `null`) - pass an empty object `{}` or a previously used `nameCache` object if you wish to cache mangled variable and property names across multiple invocations of `minify()`. Note: this is a read/write property. `minify()` will read the name cache state of this object and update it during minification so that it may be reused or externally persisted by the user. - `ie8` (default `false`) - set to `true` to support IE8. - `keep_classnames` (default: `undefined`) - pass `true` to prevent discarding or mangling of class names. - `keep_fnames` (default: `false`) - pass `true` to prevent discarding or mangling of function names. Useful for code relying on `Function.prototype.name`. If the top level minify option `keep_classnames` is `undefined` it will be overriden with the value of the top level minify option `keep_fnames`. - `safari10` (default: `false`) - pass `true` to work around Safari 10/11 bugs in loop scoping and `await`. See `safari10` options in [`mangle`](#mangle-options) and [`output`](#output-options) for details. ## Minify options structure ```javascript { parse: { // parse options }, compress: { // compress options }, mangle: { // mangle options properties: { // mangle property options } }, output: { // output options }, sourceMap: { // source map options }, ecma: 5, // specify one of: 5, 6, 7 or 8 keep_classnames: false, keep_fnames: false, ie8: false, nameCache: null, // or specify a name cache object safari10: false, toplevel: false, warnings: false, } ``` ### Source map options To generate a source map: ```javascript var result = UglifyJS.minify({"file1.js": "var a = function() {};"}, { sourceMap: { filename: "out.js", url: "out.js.map" } }); console.log(result.code); // minified output console.log(result.map); // source map ``` Note that the source map is not saved in a file, it's just returned in `result.map`. The value passed for `sourceMap.url` is only used to set `//# sourceMappingURL=out.js.map` in `result.code`. The value of `filename` is only used to set `file` attribute (see [the spec][sm-spec]) in source map file. You can set option `sourceMap.url` to be `"inline"` and source map will be appended to code. You can also specify sourceRoot property to be included in source map: ```javascript var result = UglifyJS.minify({"file1.js": "var a = function() {};"}, { sourceMap: { root: "http://example.com/src", url: "out.js.map" } }); ``` If you're compressing compiled JavaScript and have a source map for it, you can use `sourceMap.content`: ```javascript var result = UglifyJS.minify({"compiled.js": "compiled code"}, { sourceMap: { content: "content from compiled.js.map", url: "minified.js.map" } }); // same as before, it returns `code` and `map` ``` If you're using the `X-SourceMap` header instead, you can just omit `sourceMap.url`. ## Parse options - `bare_returns` (default `false`) -- support top level `return` statements - `ecma` (default: `8`) -- specify one of `5`, `6`, `7` or `8`. Note: this setting is not presently enforced except for ES8 optional trailing commas in function parameter lists and calls with `ecma` `8`. - `html5_comments` (default `true`) - `shebang` (default `true`) -- support `#!command` as the first line ## Compress options - `arrows` (default: `true`) -- Converts `()=>{return x}` to `()=>x`. Class and object literal methods will also be converted to arrow expressions if the resultant code is shorter: `m(){return x}` becomes `m:()=>x`. This transform requires that the `ecma` compress option is set to `6` or greater. - `booleans` (default: `true`) -- various optimizations for boolean context, for example `!!a ? b : c → a ? b : c` - `collapse_vars` (default: `true`) -- Collapse single-use non-constant variables, side effects permitting. - `comparisons` (default: `true`) -- apply certain optimizations to binary nodes, e.g. `!(a <= b) → a > b` (only when `unsafe_comps`), attempts to negate binary nodes, e.g. `a = !b && !c && !d && !e → a=!(b||c||d||e)` etc. - `computed_props` (default: `true`) -- Transforms constant computed properties into regular ones: `{["computed"]: 1}` is converted to `{computed: 1}`. - `conditionals` (default: `true`) -- apply optimizations for `if`-s and conditional expressions - `dead_code` (default: `true`) -- remove unreachable code - `drop_console` (default: `false`) -- Pass `true` to discard calls to `console.*` functions. If you wish to drop a specific function call such as `console.info` and/or retain side effects from function arguments after dropping the function call then use `pure_funcs` instead. - `drop_debugger` (default: `true`) -- remove `debugger;` statements - `ecma` (default: `5`) -- Pass `6` or greater to enable `compress` options that will transform ES5 code into smaller ES6+ equivalent forms. - `evaluate` (default: `true`) -- attempt to evaluate constant expressions - `expression` (default: `false`) -- Pass `true` to preserve completion values from terminal statements without `return`, e.g. in bookmarklets. - `global_defs` (default: `{}`) -- see [conditional compilation](#conditional-compilation) - `hoist_funs` (default: `false`) -- hoist function declarations - `hoist_props` (default: `true`) -- hoist properties from constant object and array literals into regular variables subject to a set of constraints. For example: `var o={p:1, q:2}; f(o.p, o.q);` is converted to `f(1, 2);`. Note: `hoist_props` works best with `mangle` enabled, the `compress` option `passes` set to `2` or higher, and the `compress` option `toplevel` enabled. - `hoist_vars` (default: `false`) -- hoist `var` declarations (this is `false` by default because it seems to increase the size of the output in general) - `if_return` (default: `true`) -- optimizations for if/return and if/continue - `inline` (default: `true`) -- inline calls to function with simple/`return` statement: - `false` -- same as `0` - `0` -- disabled inlining - `1` -- inline simple functions - `2` -- inline functions with arguments - `3` -- inline functions with arguments and variables - `true` -- same as `3` - `join_vars` (default: `true`) -- join consecutive `var` statements - `keep_classnames` (default: `false`) -- Pass `true` to prevent the compressor from discarding class names. See also: the `keep_classnames` [mangle option](#mangle). - `keep_fargs` (default: `true`) -- Prevents the compressor from discarding unused function arguments. You need this for code which relies on `Function.length`. - `keep_fnames` (default: `false`) -- Pass `true` to prevent the compressor from discarding function names. Useful for code relying on `Function.prototype.name`. See also: the `keep_fnames` [mangle option](#mangle). - `keep_infinity` (default: `false`) -- Pass `true` to prevent `Infinity` from being compressed into `1/0`, which may cause performance issues on Chrome. - `loops` (default: `true`) -- optimizations for `do`, `while` and `for` loops when we can statically determine the condition. - `negate_iife` (default: `true`) -- negate "Immediately-Called Function Expressions" where the return value is discarded, to avoid the parens that the code generator would insert. - `passes` (default: `1`) -- The maximum number of times to run compress. In some cases more than one pass leads to further compressed code. Keep in mind more passes will take more time. - `properties` (default: `true`) -- rewrite property access using the dot notation, for example `foo["bar"] → foo.bar` - `pure_funcs` (default: `null`) -- You can pass an array of names and UglifyJS will assume that those functions do not produce side effects. DANGER: will not check if the name is redefined in scope. An example case here, for instance `var q = Math.floor(a/b)`. If variable `q` is not used elsewhere, UglifyJS will drop it, but will still keep the `Math.floor(a/b)`, not knowing what it does. You can pass `pure_funcs: [ 'Math.floor' ]` to let it know that this function won't produce any side effect, in which case the whole statement would get discarded. The current implementation adds some overhead (compression will be slower). - `pure_getters` (default: `"strict"`) -- If you pass `true` for this, UglifyJS will assume that object property access (e.g. `foo.bar` or `foo["bar"]`) doesn't have any side effects. Specify `"strict"` to treat `foo.bar` as side-effect-free only when `foo` is certain to not throw, i.e. not `null` or `undefined`. - `reduce_funcs` (default: `true`) -- Allows single-use functions to be inlined as function expressions when permissible allowing further optimization. Enabled by default. Option depends on `reduce_vars` being enabled. Some code runs faster in the Chrome V8 engine if this option is disabled. Does not negatively impact other major browsers. - `reduce_vars` (default: `true`) -- Improve optimization on variables assigned with and used as constant values. - `sequences` (default: `true`) -- join consecutive simple statements using the comma operator. May be set to a positive integer to specify the maximum number of consecutive comma sequences that will be generated. If this option is set to `true` then the default `sequences` limit is `200`. Set option to `false` or `0` to disable. The smallest `sequences` length is `2`. A `sequences` value of `1` is grandfathered to be equivalent to `true` and as such means `200`. On rare occasions the default sequences limit leads to very slow compress times in which case a value of `20` or less is recommended. - `side_effects` (default: `true`) -- Pass `false` to disable potentially dropping functions marked as "pure". A function call is marked as "pure" if a comment annotation `/*@__PURE__*/` or `/*#__PURE__*/` immediately precedes the call. For example: `/*@__PURE__*/foo();` - `switches` (default: `true`) -- de-duplicate and remove unreachable `switch` branches - `toplevel` (default: `false`) -- drop unreferenced functions (`"funcs"`) and/or variables (`"vars"`) in the top level scope (`false` by default, `true` to drop both unreferenced functions and variables) - `top_retain` (default: `null`) -- prevent specific toplevel functions and variables from `unused` removal (can be array, comma-separated, RegExp or function. Implies `toplevel`) - `typeofs` (default: `true`) -- Transforms `typeof foo == "undefined"` into `foo === void 0`. Note: recommend to set this value to `false` for IE10 and earlier versions due to known issues. - `unsafe` (default: `false`) -- apply "unsafe" transformations (discussion below) - `unsafe_arrows` (default: `false`) -- Convert ES5 style anonymous function expressions to arrow functions if the function body does not reference `this`. Note: it is not always safe to perform this conversion if code relies on the the function having a `prototype`, which arrow functions lack. This transform requires that the `ecma` compress option is set to `6` or greater. - `unsafe_comps` (default: `false`) -- Reverse `<` and `<=` to `>` and `>=` to allow improved compression. This might be unsafe when an at least one of two operands is an object with computed values due the use of methods like `get`, or `valueOf`. This could cause change in execution order after operands in the comparison are switching. Compression only works if both `comparisons` and `unsafe_comps` are both set to true. - `unsafe_Function` (default: `false`) -- compress and mangle `Function(args, code)` when both `args` and `code` are string literals. - `unsafe_math` (default: `false`) -- optimize numerical expressions like `2 * x * 3` into `6 * x`, which may give imprecise floating point results. - `unsafe_methods` (default: false) -- Converts `{ m: function(){} }` to `{ m(){} }`. `ecma` must be set to `6` or greater to enable this transform. If `unsafe_methods` is a RegExp then key/value pairs with keys matching the RegExp will be converted to concise methods. Note: if enabled there is a risk of getting a "`` is not a constructor" TypeError should any code try to `new` the former function. - `unsafe_proto` (default: `false`) -- optimize expressions like `Array.prototype.slice.call(a)` into `[].slice.call(a)` - `unsafe_regexp` (default: `false`) -- enable substitutions of variables with `RegExp` values the same way as if they are constants. - `unsafe_undefined` (default: `false`) -- substitute `void 0` if there is a variable named `undefined` in scope (variable name will be mangled, typically reduced to a single character) - `unused` (default: `true`) -- drop unreferenced functions and variables (simple direct variable assignments do not count as references unless set to `"keep_assign"`) - `warnings` (default: `false`) -- display warnings when dropping unreachable code or unused declarations etc. ## Mangle options - `eval` (default `false`) -- Pass `true` to mangle names visible in scopes where `eval` or `with` are used. - `keep_classnames` (default `false`) -- Pass `true` to not mangle class names. See also: the `keep_classnames` [compress option](#compress-options). - `keep_fnames` (default `false`) -- Pass `true` to not mangle function names. Useful for code relying on `Function.prototype.name`. See also: the `keep_fnames` [compress option](#compress-options). - `reserved` (default `[]`) -- Pass an array of identifiers that should be excluded from mangling. Example: `["foo", "bar"]`. - `toplevel` (default `false`) -- Pass `true` to mangle names declared in the top level scope. - `safari10` (default `false`) -- Pass `true` to work around the Safari 10 loop iterator [bug](https://bugs.webkit.org/show_bug.cgi?id=171041) "Cannot declare a let variable twice". See also: the `safari10` [output option](#output-options). Examples: ```javascript // test.js var globalVar; function funcName(firstLongName, anotherLongName) { var myVariable = firstLongName + anotherLongName; } ``` ```javascript var code = fs.readFileSync("test.js", "utf8"); UglifyJS.minify(code).code; // 'function funcName(a,n){}var globalVar;' UglifyJS.minify(code, { mangle: { reserved: ['firstLongName'] } }).code; // 'function funcName(firstLongName,a){}var globalVar;' UglifyJS.minify(code, { mangle: { toplevel: true } }).code; // 'function n(n,a){}var a;' ``` ### Mangle properties options - `builtins` (default: `false`) -- Use `true` to allow the mangling of builtin DOM properties. Not recommended to override this setting. - `debug` (default: `false`) -— Mangle names with the original name still present. Pass an empty string `""` to enable, or a non-empty string to set the debug suffix. - `keep_quoted` (default: `false`) -— Only mangle unquoted property names. - `regex` (default: `null`) -— Pass a RegExp literal to only mangle property names matching the regular expression. - `reserved` (default: `[]`) -- Do not mangle property names listed in the `reserved` array. ## Output options The code generator tries to output shortest code possible by default. In case you want beautified output, pass `--beautify` (`-b`). Optionally you can pass additional arguments that control the code output: - `ascii_only` (default `false`) -- escape Unicode characters in strings and regexps (affects directives with non-ascii characters becoming invalid) - `beautify` (default `true`) -- whether to actually beautify the output. Passing `-b` will set this to true, but you might need to pass `-b` even when you want to generate minified code, in order to specify additional arguments, so you can use `-b beautify=false` to override it. - `bracketize` (default `false`) -- always insert brackets in `if`, `for`, `do`, `while` or `with` statements, even if their body is a single statement. - `comments` (default `false`) -- pass `true` or `"all"` to preserve all comments, `"some"` to preserve some comments, a regular expression string (e.g. `/^!/`) or a function. - `ecma` (default `5`) -- set output printing mode. Set `ecma` to `6` or greater to emit shorthand object properties - i.e.: `{a}` instead of `{a: a}`. The `ecma` option will only change the output in direct control of the beautifier. Non-compatible features in the abstract syntax tree will still be output as is. For example: an `ecma` setting of `5` will **not** convert ES6+ code to ES5. - `indent_level` (default `4`) - `indent_start` (default `0`) -- prefix all lines by that many spaces - `inline_script` (default `false`) -- escape the slash in occurrences of `

Dependencys

GroupId ArtifactID Version 引用量
TJ Holowaychuk commander 5.0.0 40972
Nick Fitzgerald source-map 0.7.3 1846

开发依赖

GroupId ArtifactID Version 引用量
adrianheine acorn 6.4.1 2702
adam_baldwin semver 7.1.3 20807