source-map-builder

A better libaray to consume, generate and merge source maps.

Install

$ npm install source-map-builder

Table of Contents

• Examples
  • Consuming a source map
  • Generating a source map
  • Merging source maps
• API
  • new SourceMapBuilder(sourceMapData?)
  • SourceMapBuilder.prototype.getSource(line, number)
  • SourceMapBuilder.prototype.eachMapping(callback, scope?)
  • SourceMapBuilder.prototype.addMapping(line, column, sourcePath?, sourceLine?, sourceColumn? name?)
  • SourceMapBuilder.prototype.addSource(sourcePath, sourceContent?)
  • SourceMapBuilder.prototype.addName(name)
  • SourceMapBuilder.prototype.setSourceContent(sourcePath, sourceContent)
  • SourceMapBuilder.prototype.getSourceContent(sourcePath)
  • SourceMapBuilder.prototype.applySourceMap(other, file)
  • SourceMapBuilder.prototype.toJSON()
  • SourceMapBuilder.prototype.toString()
  • SourceMapBuilder.prototype.computeLines()
  • emitSourceMapUrl(content, sourceMapUrl, singleLineComment?)

Examples

Consuming a source map

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 sourceMap = require("source-map-builder");
var smb = new sourceMap.SourceMapBuilder(rawSourceMap);
 
console.log(smb.getSource(1, 28));
// { sourcePath: 'http://example.com/www/js/two.js',
//    line: 1,
//    column: 10,
//    name: 'n' }
 
smb.eachMapping(function(line, column, sourcePath, sourceContent, sourceLine, sourceColumn, name) {
    // ...
});

Generating a source map

var sourceMap = require("source-map-builder");
var smb = new sourceMap.SourceMapBuilder({
  file: "source-mapped.js"
});
 
smb.addMapping(9, 35, "foo.js", 32, 2, "christopher");
 
console.log(smb.toJSON());
// { version: 3,
//   sources: [ 'foo.js' ],
//   mappings: ';;;;;;;;;mCAgCEA',
//   names: [ 'christopher' ] }

Merging source maps

var sourceMap = require("source-map-builder");
var smb1 = new sourceMap.SourceMapBuilder();
var smb2 = new sourceMap.SourceMapBuilder();
 
smb1.applySourceMap(smb2);

API

new SourceMapBuilder(sourceMapData?)

An instance of the SourceMapBuilder represents a source map which is being built incrementally. You may pass a raw source map data(eithor a string or a json) if you want to create a source map based on an existing one.

// Create an empty source map.
var smb = new SourceMapBuilder(); 

// Creates a source map from an existing source map.
var smb = new SourceMapBuilder('{"version":3,"file":"source-mapped.js","sources":["foo.js"],"names":["christopher"],"mappings":";;;;;;;;;mCAgCEA"}'); 

SourceMapBuilder.prototype.getSource(line, number)

Returns the original source, line, and column information for the generated source's line and column positions provided.

• line: The 0-based line number in the generated source.
• column: The 0-based column number in the generated source.

The object returned has the following properties:

• sourcePath: The original source file, or undefined if this information is not available.
• sourceContent: The original source content, or undefined if this information is not available.
• line: The 0-based line number in the original source, or undefined if this information is not available.
• column: The 0-based column number in the original source, or undefined if this information is not available.
• name: The original identifier, or undefined if this information is not available.

SourceMapBuilder.prototype.eachMapping(callback, scope?)

Iterate over each mapping between an original source/line/column and a generated line/column in this source smb.

• callback: The function that is called with each mapping. callback receives these arguments:
  • line: The 0-based line number in the generated source.
  • column: The 0-based column number in the generated source.
  • sourcePath: The original source file, or undefined if this information is not available.
  • sourceContent: The original source content, or undefined if this information is not available.
  • sourceLine: The 0-based line number in the original source, or undefined if this information is not available.
  • sourceColumn: The 0-based column number in the original source, or undefined if this information is not available.
  • name: The original identifier, or undefined if this information is not available.
• scope: Optional. If specified, this object will be the value of this every time that callback is called.

smb.eachMapping(function(line, column, sourcePath, sourceContent, sourceLine, sourceColumn, name) {
    console.log(line, column, sourcePath, sourceContent, sourceLine, sourceColumn, name);
});

SourceMapBuilder.prototype.addMapping(line, column, sourcePath?, sourceLine?, sourceColumn? name?)

Add a single mapping from original source line and column to the generated source's line and column for this source map being created.

• line: The 0-based line number in the generated source.
• column: The 0-based column number in the generated source.
• sourcePath: Optional. The original source file.
• sourceContent: Optional. The original source content.
• sourceLine: Optional. The 0-based line number in the original source.
• sourceColumn: Optional. The 0-based column number in the original source.

smb.addMapping(1, 2, "module-one.scm", 4, 5);

SourceMapBuilder.prototype.addSource(sourcePath, sourceContent?)

Add a source and return the source index.

• sourcePath: The original source file.
• sourceContent: Optional. The original source content.

var sourceIndex = smb.addSource("module-one.scm");

SourceMapBuilder.prototype.addName(name)

Add a source and return the name index.

• name: The original identifier.

var nameIndex = smb.addName("smb");

SourceMapBuilder.prototype.setSourceContent(sourcePath, sourceContent)

Set the source content for an original source file.

• sourcePath: The original source file.
• sourceContent: The original source content.

smb.setSourceContent("module-one.scm", fs.readFileSync("path/to/module-one.scm"));

SourceMapBuilder.prototype.getSourceContent(sourcePath)

Get the source content for an original source file.

• sourcePath: The original source file.

var content = smb.getSourceContent("module-one.scm");

SourceMapBuilder.prototype.applySourceMap(other, file)

Applies a SourceMap for a source file to the Sourcesmb. Each mapping to the supplied source file is rewritten using the supplied Sourcesmb.

• other: Another source map builder to apply.
• file: Optional. The filename of the source file. If omitted, other.file will be used, if it exists. Otherwise an error will be thrown.

var content = smb.getSourceContent("module-one.scm");

SourceMapBuilder.prototype.toJSON()

Renders the source map being generated to a json.

smb.toJSON()
// {"version":3,"sources":["module-one.scm"],"names":[],"mappings":"...snip...","file":"my-generated-javascript-file.js","sourceRoot":"http://example.com/app/js/"}

SourceMapBuilder.prototype.toString()

Renders the source map being generated to a string.

smb.toString()
// generator.toString()
// '{"version":3,"sources":["module-one.scm"],"names":[],"mappings":"...snip...","file":"my-generated-javascript-file.js","sourceRoot":"http://example.com/app/js/"}'

SourceMapBuilder.prototype.computeLines()

Compute the missing line mappings.

// Before:
smb.mappings
// [ undefined, undefined, [line:2, column: 1] ]
 
smb.computeLines()
 
// After:
smb.mappings
// [ [line: 0, column: 0], [line:1, column: 0], [line:2, column: 1] ]
 

emitSourceMapUrl(content, sourceMapUrl, singleLineComment?)

Emit a #sourceMappingURL comment into content.

• content: The source content to emit.
• sourceMapUrl: The source map url to emit.
• singleLineComment: Optional. If set to true, prefer emiting // #sourceMappingURL.

var result = emitSourceMapUrl("", "foo.js.map");
// "\n/* #sourceMappingURL=foo.js.map */"