Package Exports

merge-source-map

This package does not declare an exports field, so the exports above have been automatically detected and optimized by JSPM instead. If any package subpath is missing, it is recommended to post an issue to the original package (merge-source-map) to support the "exports" field. If that is not possible, create a JSPM override to customize the exports field for this package.

Readme

merge-source-map

Merge old source map and new source map in multi-transform flow

API

var merge = require('merge-source-map')

`merge(oldMap, newMap)`

Merge old source map and new source map and return merged. If old or new source map value is falsy, return another one as it is.

oldMap : object|undefined: old source map object
newmap : object|undefined: new source map object

Example

var esprima    = require('esprima'),
    estraverse = require('estraverse'),
    escodegen  = require('escodegen'),
    convert    = require('convert-source-map'),
    merge      = require('merge-source-map')

const CODE = 'a = 1',
      FILEPATH = 'a.js'

// create AST of original code
var ast = esprima.parse(CODE, {sourceType: 'module', loc: true})

// transform AST of original code
estraverse.replace(ast, {
  enter: function(node, parent) { /* change AST */ },
  leave: function(node, parent) { /* change AST */ }
})

// generate code and source map from transformed AST
var gen = escodegen.generate(ast, {
  sourceMap: FILEPATH,
  sourceMapWithCode: true,
  sourceContent: CODE
})

// merge old source map and new source map
var oldMap = convert.fromSource(CODE) && convert.fromSource(CODE).toObject(),
    newMap = JSON.parse(gen.map.toString()),
    mergedMap = merge(oldMap, newMap),
    mapComment = convert.fromObject(mergedMap).toComment()

// attach merge source map to transformed code
var transformed = gen.code + '\n' + mapComment

console.log(transformed);

Test

% npm install
% npm test

License

MIT (c) keik