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# Source Map [](https://travis-ci.org/mozilla/source-map) [](https://www.npmjs.com/package/source-map) This is a library to generate and consume the source map format [described here][format]. [format]: https://docs.google.com/document/d/1U1RGAehQwRypUTovF1KRlpiOFze0b-_2gc6fAH0KY0k/edit ## Use with Node $ npm install source-map ## Use on the Web <script src="https://raw.githubusercontent.com/mozilla/source-map/master/dist/source-map.min.js" defer></script> -------------------------------------------------------------------------------- <!-- `npm run toc` to regenerate the Table of Contents --> <!-- START doctoc generated TOC please keep comment here to allow auto update --> <!-- DON'T EDIT THIS SECTION, INSTEAD RE-RUN doctoc TO UPDATE --> ## Table of Contents - [Examples](#examples) - [Consuming a source map](#consuming-a-source-map) - [Generating a source map](#generating-a-source-map) - [With SourceNode (high level API)](#with-sourcenode-high-level-api) - [With SourceMapGenerator (low level API)](#with-sourcemapgenerator-low-level-api) - [API](#api) - [SourceMapConsumer](#sourcemapconsumer) - [new SourceMapConsumer(rawSourceMap)](#new-sourcemapconsumerrawsourcemap) - [SourceMapConsumer.prototype.computeColumnSpans()](#sourcemapconsumerprototypecomputecolumnspans) - [SourceMapConsumer.prototype.originalPositionFor(generatedPosition)](#sourcemapconsumerprototypeoriginalpositionforgeneratedposition) - [SourceMapConsumer.prototype.generatedPositionFor(originalPosition)](#sourcemapconsumerprototypegeneratedpositionfororiginalposition) - [SourceMapConsumer.prototype.allGeneratedPositionsFor(originalPosition)](#sourcemapconsumerprototypeallgeneratedpositionsfororiginalposition) - [SourceMapConsumer.prototype.hasContentsOfAllSources()](#sourcemapconsumerprototypehascontentsofallsources) - [SourceMapConsumer.prototype.sourceContentFor(source[, returnNullOnMissing])](#sourcemapconsumerprototypesourcecontentforsource-returnnullonmissing) - [SourceMapConsumer.prototype.eachMapping(callback, context, order)](#sourcemapconsumerprototypeeachmappingcallback-context-order) - [SourceMapGenerator](#sourcemapgenerator) - [new SourceMapGenerator([startOfSourceMap])](#new-sourcemapgeneratorstartofsourcemap) - [SourceMapGenerator.fromSourceMap(sourceMapConsumer)](#sourcemapgeneratorfromsourcemapsourcemapconsumer) - [SourceMapGenerator.prototype.addMapping(mapping)](#sourcemapgeneratorprototypeaddmappingmapping) - [SourceMapGenerator.prototype.setSourceContent(sourceFile, sourceContent)](#sourcemapgeneratorprototypesetsourcecontentsourcefile-sourcecontent) - [SourceMapGenerator.prototype.applySourceMap(sourceMapConsumer[, sourceFile[, sourceMapPath]])](#sourcemapgeneratorprototypeapplysourcemapsourcemapconsumer-sourcefile-sourcemappath) - [SourceMapGenerator.prototype.toString()](#sourcemapgeneratorprototypetostring) - [SourceNode](#sourcenode) - [new SourceNode([line, column, source[, chunk[, name]]])](#new-sourcenodeline-column-source-chunk-name) - [SourceNode.fromStringWithSourceMap(code, sourceMapConsumer[, relativePath])](#sourcenodefromstringwithsourcemapcode-sourcemapconsumer-relativepath) - [SourceNode.prototype.add(chunk)](#sourcenodeprototypeaddchunk) - [SourceNode.prototype.prepend(chunk)](#sourcenodeprototypeprependchunk) - [SourceNode.prototype.setSourceContent(sourceFile, sourceContent)](#sourcenodeprototypesetsourcecontentsourcefile-sourcecontent) - [SourceNode.prototype.walk(fn)](#sourcenodeprototypewalkfn) - [SourceNode.prototype.walkSourceContents(fn)](#sourcenodeprototypewalksourcecontentsfn) - [SourceNode.prototype.join(sep)](#sourcenodeprototypejoinsep) - [SourceNode.prototype.replaceRight(pattern, replacement)](#sourcenodeprototypereplacerightpattern-replacement) - [SourceNode.prototype.toString()](#sourcenodeprototypetostring) - [SourceNode.prototype.toStringWithSourceMap([startOfSourceMap])](#sourcenodeprototypetostringwithsourcemapstartofsourcemap) <!-- END doctoc generated TOC please keep comment here to allow auto update --> ## Examples ### Consuming a source map ```js var rawSourceMap = { version: 3, file: 'min.js', names: ['bar', 'baz', 'n'], sources: ['one.js', 'two.js'], sourceRoot: 'http://example.com/www/js/', mappings: 'CAAC,IAAI,IAAM,SAAUA,GAClB,OAAOC,IAAID;CCDb,IAAI,IAAM,SAAUE,GAClB,OAAOA' }; var smc = new SourceMapConsumer(rawSourceMap); console.log(smc.sources); // [ 'http://example.com/www/js/one.js', // 'http://example.com/www/js/two.js' ] console.log(smc.originalPositionFor({ line: 2, column: 28 })); // { source: 'http://example.com/www/js/two.js', // line: 2, // column: 10, // name: 'n' } console.log(smc.generatedPositionFor({ source: 'http://example.com/www/js/two.js', line: 2, column: 10 })); // { line: 2, column: 28 } smc.eachMapping(function (m) { // ... }); ``` ### Generating a source map In depth guide: [**Compiling to JavaScript, and Debugging with Source Maps**](https://hacks.mozilla.org/2013/05/compiling-to-javascript-and-debugging-with-source-maps/) #### With SourceNode (high level API) ```js function compile(ast) { switch (ast.type) { case 'BinaryExpression': return new SourceNode( ast.location.line, ast.location.column, ast.location.source, [compile(ast.left), " + ", compile(ast.right)] ); case 'Literal': return new SourceNode( ast.location.line, ast.location.column, ast.location.source, String(ast.value) ); // ... default: throw new Error("Bad AST"); } } var ast = parse("40 + 2", "add.js"); console.log(compile(ast).toStringWithSourceMap({ file: 'add.js' })); // { code: '40 + 2', // map: [object SourceMapGenerator] } ``` #### With SourceMapGenerator (low level API) ```js var map = new SourceMapGenerator({ file: "source-mapped.js" }); map.addMapping({ generated: { line: 10, column: 35 }, source: "foo.js", original: { line: 33, column: 2 }, name: "christopher" }); console.log(map.toString()); // '{"version":3,"file":"source-mapped.js","sources":["foo.js"],"names":["christopher"],"mappings":";;;;;;;;;mCAgCEA"}' ``` ## API Get a reference to the module: ```js // Node.js var sourceMap = require('source-map'); // Browser builds var sourceMap = window.sourceMap; // Inside Firefox const sourceMap = require("devtools/toolkit/sourcemap/source-map.js"); ``` ### SourceMapConsumer A SourceMapConsumer instance represents a parsed source map which we can query for information about the original file positions by giving it a file position in the generated source. #### new SourceMapConsumer(rawSourceMap) The only parameter is the raw source map (either as a string which can be `JSON.parse`'d, or an object). According to the spec, source maps have the following attributes: * `version`: Which version of the source map spec this map is following. * `sources`: An array of URLs to the original source files. * `names`: An array of identifiers which can be referenced by individual mappings. * `sourceRoot`: Optional. The URL root from which all sources are relative. * `sourcesContent`: Optional. An array of contents of the original source files. * `mappings`: A string of base64 VLQs which contain the actual mappings. * `file`: Optional. The generated filename this source map is associated with. ```js var consumer = new sourceMap.SourceMapConsumer(rawSourceMapJsonData); ``` #### SourceMapConsumer.prototype.computeColumnSpans() Compute the last column for each generated mapping. The last column is inclusive. ```js // Before: consumer.allGeneratedPositionsFor({ line: 2, source: "foo.coffee" }) // [ { line: 2, // column: 1 }, // { line: 2, // column: 10 }, // { line: 2