JarCastinginline-source-map 
Adds source mappings and base64 encodes them, so they can be inlined in your generated file.
var generator = require('inline-source-map');
// default charset 'utf-8' is configurable
var gen = generator({ charset: 'utf-8' })
.addMappings('foo.js', [{ original: { line: 2, column: 3 } , generated: { line: 5, column: 10 } }], { line: 5 })
.addGeneratedMappings('bar.js', 'var a = 2;\nconsole.log(a)', { line: 23, column: 22 });
console.log('base64 mapping:', gen.base64Encode());
console.log('inline mapping url:', gen.inlineMappingUrl());
base64 mapping: eyJ2ZXJzaW9uIjozLCJmaWxlIjoiIiwic291cmNlcyI6WyJmb28uanMiLCJiYXIuanMiXSwibmFtZXMiOltdLCJtYXBwaW5ncyI6Ijs7Ozs7Ozs7O1VBQ0c7Ozs7Ozs7Ozs7Ozs7O3NCQ0RIO3NCQUNBIn0=
inline mapping url: //@ sourceMappingURL=data:application/json;charset=utf-8;base64,eyJ2ZXJzaW9uIjozLCJmaWxlIjoiIiwic291cmNlcyI6WyJmb28uanMiLCJiYXIuanMiXSwibmFtZXMiOltdLCJtYXBwaW5ncyI6Ijs7Ozs7Ozs7O1VBQ0c7Ozs7Ozs7Ozs7Ozs7O3NCQ0RIO3NCQUNBIn0=
API
addMappings(sourceFile, mappings, offset)
/**
* Adds the given mappings to the generator and offsets them if offset is given
*
* @name addMappings
* @function
* @param sourceFile {String} name of the source file
* @param mappings {Array{{Object}} each object has the form { original: { line: _, column: _ }, generated: { line: _, column: _ } }
* @param offset {Object} offset to apply to each mapping. Has the form { line: _, column: _ }
* @return {Object} the generator to allow chaining
*/
addGeneratedMappings(sourceFile, source, offset)
/**
* Generates mappings for the given source and adds them, assuming that no translation from original to generated is necessary.
*
* @name addGeneratedMappings
* @function
* @param sourceFile {String} name of the source file
* @param source {String} source of the file
* @param offset {Object} offset to apply to each mapping. Has the form { line: _, column: _ }
* @return {Object} the generator to allow chaining
*/
addSourceContent(sourceFile, sourceContent)
/**
* Adds source content for the given source file.
*
* @name addSourceContent
* @function
* @param sourceFile {String} The source file for which a mapping is included
* @param sourceContent {String} The content of the source file
* @return {Object} The generator to allow chaining
*/
base64Encode()
/**
* @name base64Encode
* @function
* @return {String} bas64 encoded representation of the added mappings
*/
If source contents were added, this will be included in the encoded mappings.
inlineMappingUrl()
/**
* @name inlineMappingUrl
* @function
* @return {String} comment with base64 encoded representation of the added mappings. Can be inlined at the end of the generated file.
*/