module-deps

What is module-deps?

The module-deps npm package is a tool for analyzing the dependency graph of Node.js modules. It parses the require() calls in a given entry file and recursively resolves the dependencies, providing a detailed graph of all the modules and their interconnections.

What are module-deps's main functionalities?

Dependency Graph Generation

This feature allows you to generate a JSON file that represents the dependency graph of a given entry file. The code sample demonstrates how to use module-deps to analyze 'entry.js' and output the dependency graph to 'deps.json'.

const mdeps = require('module-deps');
const JSONStream = require('JSONStream');
const fs = require('fs');

const md = mdeps();
md.pipe(JSONStream.stringify()).pipe(fs.createWriteStream('deps.json'));
md.end({ file: 'entry.js' });

Custom Resolvers

This feature allows you to provide custom resolution logic for resolving module paths. The code sample shows how to use a custom resolver function to handle module resolution.

const mdeps = require('module-deps');
const JSONStream = require('JSONStream');
const fs = require('fs');

const md = mdeps({
  resolve: (id, parent, cb) => {
    // Custom resolution logic
    cb(null, id);
  }
});
md.pipe(JSONStream.stringify()).pipe(fs.createWriteStream('deps.json'));
md.end({ file: 'entry.js' });

Transform Streams

This feature allows you to apply transform streams to the source files before they are parsed. The code sample demonstrates how to replace all instances of 'require' with 'customRequire' in the source files.

const mdeps = require('module-deps');
const through = require('through2');
const JSONStream = require('JSONStream');
const fs = require('fs');

const md = mdeps({
  transform: (file) => {
    return through(function (buf, enc, next) {
      this.push(buf.toString('utf8').replace(/require/g, 'customRequire'));
      next();
    });
  }
});
md.pipe(JSONStream.stringify()).pipe(fs.createWriteStream('deps.json'));
md.end({ file: 'entry.js' });

Other packages similar to module-deps

browserify

Browserify is a tool that allows you to bundle up all of your JavaScript dependencies for the browser. It also provides a way to analyze the dependency graph of your modules. Compared to module-deps, Browserify offers a more comprehensive solution for bundling and dependency management, including support for various plugins and transforms.

webpack

Webpack is a powerful module bundler for JavaScript applications. It analyzes the dependency graph of your modules and bundles them into a single file or multiple chunks. Webpack provides a rich ecosystem of plugins and loaders, making it more versatile than module-deps for complex build processes.

rollup

Rollup is a module bundler for JavaScript that focuses on ES6 modules. It provides tree-shaking capabilities to remove unused code from the final bundle. While module-deps focuses on dependency graph analysis, Rollup is more geared towards optimizing and bundling ES6 modules.

README

module-deps

walk the dependency graph to generate json output that can be fed into browser-pack

example

var mdeps = require('module-deps');
var JSONStream = require('JSONStream');

var md = mdeps();
md.pipe(JSONStream.stringify()).pipe(process.stdout);
md.end({ file: __dirname + '/files/main.js' });

output:

$ node example/deps.js
[
{"id":"/home/substack/projects/module-deps/example/files/main.js","source":"var foo = require('./foo');\nconsole.log('main: ' + foo(5));\n","entry":true,"deps":{"./foo":"/home/substack/projects/module-deps/example/files/foo.js"}}
,
{"id":"/home/substack/projects/module-deps/example/files/foo.js","source":"var bar = require('./bar');\n\nmodule.exports = function (n) {\n    return n * 111 + bar(n);\n};\n","deps":{"./bar":"/home/substack/projects/module-deps/example/files/bar.js"}}
,
{"id":"/home/substack/projects/module-deps/example/files/bar.js","source":"module.exports = function (n) {\n    return n * 100;\n};\n","deps":{}}
]

and you can feed this json data into browser-pack:

$ node example/deps.js | browser-pack | node
main: 1055

usage

usage: module-deps [files]

  generate json output from each entry file

methods

var mdeps = require('module-deps')

var d = mdeps(opts={})

Return an object transform stream d that expects entry filenames or { id: ..., file: ... } objects as input and produces objects for every dependency from a recursive module traversal as output.

Each file in files can be a string filename or a stream.

Optionally pass in some opts:

• opts.transform - a string or array of string transforms (see below)

• opts.transformKey - an array path of strings showing where to look in the package.json for source transformations. If falsy, don't look at the package.json at all.

• opts.resolve - custom resolve function using the opts.resolve(id, parent, cb) signature that browser-resolve has

• opts.detect - a custom dependency detection function. opts.detect(source) should return an array of dependency module names. By default detective is used.

• opts.filter - a function (id) to skip resolution of some module id strings. If defined, opts.filter(id) should return truthy for all the ids to include and falsey for all the ids to skip.

• opts.postFilter - a function (id, file, pkg) that gets called after id has been resolved. Return false to skip this file.

• opts.packageFilter - transform the parsed package.json contents before using the values. opts.packageFilter(pkg, dir) should return the new pkg object to use.

• opts.noParse - an array of absolute paths to not parse for dependencies. Use this for large dependencies like jquery or threejs which take forever to parse.

• opts.cache - an object mapping filenames to file objects to skip costly io

• opts.packageCache - an object mapping filenames to their parent package.json contents for browser fields, main entries, and transforms

• opts.fileCache - an object mapping filenames to raw source to avoid reading from disk.

• opts.persistentCache - a complex cache handler that allows async and persistent caching of data. A persistentCache needs to follow this interface:

  function persistentCache (
      file, // the path to the file that is loaded
      id,   // the id that is used to reference this file
      pkg,  // the package that this file belongs to fallback
      fallback, // async fallback handler to be called if the cache doesn't hold the given file 
      cb    // callback handler that receives the cache data
  ) {
      if (hasError()) {
          return cb(error) // Pass any error to the callback
      }
  
      var fileData = fs.readFileSync(file)
      var key = keyFromFile(file, fileData)
  
      if (db.has(key)) {
          return cb(null, {
              source: db.get(key).toString(),
              package: pkg, // The package for housekeeping
              deps: {
                  'id':  // id that is used to reference a required file
                  'file' // file path to the required file
              }
          })
      }
      //
      // The fallback will process the file in case the file is not
      // in cache.
      //
      // Note that if your implementation doesn't need the file data
      // then you can pass `null` instead of the source and the fallback will
      // fetch the data by itself.
      //
      fallback(fileData, function (error, cacheableEntry) {
          if (error) {
              return cb(error)
          }
          db.addToCache(key, cacheableEntry)
          cb(null, cacheableEntry)
      })
  }
  

• opts.paths - array of global paths to search. Defaults to splitting on ':' in process.env.NODE_PATH

• opts.ignoreMissing - ignore files that failed to resolve

input objects

Input objects should be string filenames or objects with these parameters:

• row.file - filename
• row.entry - whether to treat this file as an entry point, defaults to true. Set to false to include this file, but not run it automatically.
• row.expose - name to be exposed as
• row.noparse - when true, don't parse the file contents for dependencies

or objects can specify transforms:

• row.transform - string name, path, or function
• row.options - transform options as an object
• row.global - boolean, whether the transform is global

output objects

Output objects describe files with dependencies. They have these properties:

• row.id - an identifier for the file, used in the row.deps prperty
• row.file - path to the source file
• row.entry - true if the file is an entry point
• row.expose - name to be exposed as
• row.source - source file content as a string
• row.deps - object describing dependencies. The keys are strings as used in require() calls in the file, and values are the row IDs (file paths) of dependencies.

events

d.on('transform', function (tr, file) {})

Every time a transform is applied to a file, a 'transform' event fires with the instantiated transform stream tr.

d.on('file', function (file) {})

Every time a file is read, this event fires with the file path.

d.on('missing', function (id, parent) {})

When opts.ignoreMissing is enabled, this event fires for each missing package.

d.on('package', function (pkg) {})

Every time a package is read, this event fires. The directory name of the package is available in pkg.__dirname.

transforms

module-deps can be configured to run source transformations on files before parsing them for require() calls. These transforms are useful if you want to compile a language like coffeescript on the fly or if you want to load static assets into your bundle by parsing the AST for fs.readFileSync() calls.

If the transform is a function, it should take the file name as an argument and return a through stream that will be written file contents and should output the new transformed file contents.

If the transform is a string, it is treated as a module name that will resolve to a module that is expected to follow this format:

var through = require('through2');
module.exports = function (file, opts) { return through() };

You don't necessarily need to use the through2 module to create a readable/writable filter stream for transforming file contents, but this is an easy way to do it.

module-deps looks for require() calls and adds their arguments as dependencies of a file. Transform streams can emit 'dep' events to include additional dependencies that are not consumed with require().

When you call mdeps() with an opts.transform, the transformations you specify will not be run for any files in node_modules/. This is because modules you include should be self-contained and not need to worry about guarding themselves against transformations that may happen upstream.

Modules can apply their own transformations by setting a transformation pipeline in their package.json at the opts.transformKey path. These transformations only apply to the files directly in the module itself, not to the module's dependants nor to its dependencies.

package.json transformKey

Transform keys live at a configurable location in the package.json denoted by the opts.transformKey array.

For a transformKey of ['foo','bar'], the transformKey can be a single string ("fff"):

{
  "foo": {
    "bar": "fff"
  }
}

or an array of strings (["fff","ggg"]):

{
  "foo": {
    "bar": ["fff","ggg"]
  }
}

If you want to pass options to the transforms, you can use a 2-element array inside of the primary array. Here fff gets an options object with {"x":3} and ggg gets {"y":4}:

{
  "foo": {
    "bar": [["fff",{"x":3}],["ggg",{"y":4}]]
  }
}

Options sent to the module-deps constructor are also provided under opts._flags. These options are sometimes required if your transform needs to do something different when browserify is run in debug mode, for example.

usage

module-deps [FILES] OPTIONS

  Generate json output for the entry point FILES.

OPTIONS are:

  -t TRANSFORM  Apply a TRANSFORM.
  -g TRANSFORM  Apply a global TRANSFORM.

install

With npm, to get the module do:

npm install module-deps

and to get the module-deps command do:

npm install -g module-deps

license

MIT

Changelog

6.2.3 - 2020-08-03

• Improve error message when dependencies cannot be found #123
• Upgrade browser-resolve to 2.0 #164