Rewrite (alias) and expose `require()` IDs in browserify.

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2750.5.09 years ago9 years agoMinified + gzip package size for pathmodify in KB


This is a browserify plugin that's meant to do the same kind of thing as aliasify and remapify, but in a more elegant, powerful way. This hasn't been tested extensively yet, so consider it experimental. But some of the other alternatives already in common use don't really even work, so....
Installation & Quick Summary
npm install pathmodify
var pathmodify = require('pathmodify');

// Make bundled code like:
// `require('app/something')`
// act like:
// `require('/somedir/src/something')`
  .plugin(pathmodify, {mods: [
    pathmodify.mod.dir('app', '/somedir/src')
Avoid having to use cumbersome relative paths (../../../../../../..) in your browserified application, and still be able to apply transforms programatically: browserify().transform(something).
This plugin allows you to:
  • Rewrite (AKA alias, map) require() IDs / paths to different values. For example, rewrite require('app/model/something') to an absolute path like /somedir/model/something. This can be used to alias entire directories or any specific module ID or path passed to require(), and the rewriting can be dependent on the path of the requiring file as well.

  • And / or expose modules via the require function exported by the bundle, like b.require("something", {expose: "whatever"}).

Say you have a directory structure like...
+-- src/
    +-- entry.js
    +-- model/
    ¦   +-- whatever.js
    +-- subdir/
        +-- subsubdir/
            +-- something.js
...and entry.js is the entry point to a dependency graph with a bunch of files not pictured. And say you don't want to store the application files you're going to browserify in node_modules or symlink them there because it will break programmatic application of transforms (browserify().transform(whatever)). (But, see below -- you can combine this tool with symlinking to get the best of both worlds.)
pathmodify allows you to require() files like somedir/src/model/whatever.js from anywhere in the dependency graph without using ./ or ../ relative paths, enabling a something.js like this for example:
Example usage
  path = require('path'),
  pathmodify = require('pathmodify');

var opts = {
  // Feel free to think of `mods` as referring to either modifications or
  // module IDs that are being altered. It is an array of possible
  // modifications to apply to the values passed to `require()` calls in the
  // browserified code. `mods` will be iterated until an entry is
  // encountered that alters the `id` of the `require()` call being
  // processed.
  mods: [
    // `id` type (exact match)'jquery', '/somedir/jquery.js'),

    // `dir` type (directory prefix)
    pathmodify.mod.dir('app', '/somedir/src'),

    // `re` type (regular expression)*\.)abc$/, '$'),

    // Function
    function (rec) {
      var alias = {};

      var prefix = 'app' + path.sep;
      if ( === 0) { = path.join(
          __dirname, 'src',

      return alias;

  .plugin(pathmodify, opts)

When the mod is a function it will receive an object like this:
  // The string passed to `require()`
  id: '...',

  opts: {
    // Absolute path of the parent file (the one that called require())
    filename: '...'

It should leave the passed object alone and return an object like this if the id should be aliased to something else:
  // The path / id that should be resolved (as if the `require()` call
  // contained this value).
  id: '...',

  // Optional name to expose the module as (like
  // b.require('x', {expose: 'whatever'}))
  expose: '...'

If you don't want to alias the id to something else, don't return anything.
As alluded to earlier, ordinarily you could store or symlink your application as something like node_modules/app and require its files from node like require('app/something/whatever'). But if you do that in browserify you lose the ability to apply transforms programatically, like:

With this plugin you can get the best of both worlds by symlinking your application under node_modules and get the normal resolution behavior in node, and use the same paths in browserify by rewriting them to absolute paths (outside of node_modules) or paths relative to the requiring file. So if you have say /somedir/src synlinked as node_modules/app, you can use pathmodify like this:
// Point browserify to `./src/...`, not `app/...`
  .plugin(pathmodify, {mods: [
    pathmodify.mod.dir('app', path.join(__dirname, 'src'))