gulp-declare

declare plugin for gulp 3

Usage

First, install gulp-declare as a development dependency:

npm install --save-dev gulp-declare

Then, add it to your gulpfile.js:

var declare = require('gulp-declare');
var concat = require('gulp-concat');

gulp.task('models', function() {
  // Define each model as a property of a namespace according to its filename
  gulp.src(['client/models/*.js'])
    .pipe(declare({
      namespace: 'MyApp.models',
      noRedeclare: true // Avoid duplicate declarations
    }))
    .pipe(concat('models.js')) // Combine into a single file
    .pipe(gulp.dest('build/js/'));
});

API

declare(options)

options.namespace

Type: String
Default: "this"

The namespace in which the file contents will be assigned. Use dot notation (e.g. MyApp.templates) for nested namespaces.

For example, if the namespace is MyApp.templates and a file is named App.Header.js, the following declaration will be added:

this["MyApp"] = this["MyApp"] || {};
this["MyApp"]["templates"] = this["MyApp"]["templates"] || {};
this["MyApp"]["templates"]["App"] = this["MyApp"]["templates"]["App"] || {};
this["MyApp"]["templates"]["App"]["Header"] = /* File contents from App.Header.js */;

If the default value of "this" is provided, namespace declaration will be determined soley by the filename and output of options.processName. That is, a file names MyApp.templates.App.Header.js will result in the same declaration as above.

options.processName

Type: Function
Default: Strip file extension

This option accepts a function which takes one argument (the path to the file) and returns a string which will be used as the key for object. By default, the filename minus the extension is used.

This function should return a namespace path in dot notation, such as Prop.sub.item, which is then combined with options.namespace. See options.namespace above for an example.

See declare.processNameByPath to generate namespace paths based on directory structure.

options.separator

Type: String
Default: \n

The separator to use between declarations.

options.noRedeclare

Type: Boolean
Default: false

If true, parts of the namespace that were declared as a result of previous files in the stream will not be redeclared. For instance, if the stream contains the following files:

• Main.Content.js
• Main.Header.js
• Main.Footer.js

And if declare is invoked with { namespace: 'MyApp', noRedeclare: true }, the contents of the streamed files will look like this:

Main.Content.js

this["MyApp"] = this["MyApp"] || {};
this["MyApp"]["Main"] = this["MyApp"]["Main"] || {};
this["MyApp"]["Main"]["Content"] = /* File contents from Main.Content.js */;

Main.Header.js

this["MyApp"]["Main"]["Header"] = /* File contents from Main.Header.js */;

Main.Footer.js

this["MyApp"]["Main"]["Footer"] = /* File contents from Main.Footer.js */;

This option makes the most sense when you're concatenating files later and want to minimize duplicate declarations. Regardless of this option, gulp-declare will never clobber existing namespaces or their properties.

options.root

Type: String
Default: this

The root object to declare the namespace within. Defaults to this (which is equal to window in the browser).

This option is prepended to the assignment statement, so special characters or operators such as - should be avoided as they will result in an invalid left-hand assignment error.

When using Node or Browserify, you can specify root: 'module.exports' with no namespace if you would like to assign as properties of an exported module:

gulp.src(['models/*.js'])
  .pipe(declare({
    root: 'module.exports', // Declare as properties of module.exports
    noRedeclare: true // Avoid duplicate declarations
  })
  .pipe(concat('models.js'))
  .pipe(gulp.dest('build/js/'));

Which results in the following templates.js:

module.exports["App"] = module.exports["App"] || {};
module.exports["App"]["Main"] = /* File contents from App.Main.js */;
module.exports["App"]["Header"] = /* File contents from App.Header.js */;
module.exports["App"]["Footer"] = /* File contents from App.Footer.js */;

declare.processNameByPath(filePath)

Pass this method as options.processName so the path within the namespace matches the path in the filesystem combined with dot notation from the filename:

gulp.src(['templates/**/*.html'])
  .pipe(domly()) // Compile HTML to document fragment builder functions
  .pipe(declare({
    namespace: 'NS', // Use NS as the base namespace
    noRedeclare: true, // Avoid duplicate declarations
    processName: declare.processNameByPath // Include the path as part of the sub-namespace
  })
  .pipe(concat('models.js'))
  .pipe(gulp.dest('build/js/'));

The above configuration will result in the following mapping:

File path	Namespace path
templates/App.hbs	NS.templates.App
templates/App/header.hbs	NS.templates.App.header
templates/App/content.initial.hbs	NS.templates.App.content.initial
templates/Other.item.hbs	NS.templates.Other.item

Note: In the above example, NS.templates.App.header is a function that is stored as a property of the NS.templates.App function. As everything in JavaScript is an object, even functions, this is perfectly valid and works in all environments. If this hurts your brain, store templates/App.hbs as templates/App/main.hbs and access it as NS.templates.App.main.

Customizing the path used to generate the namespace

If you want to remove or change part of the path, you can define your own options.processName and use declare.processNameByPath() within it. The following example results in the same namespace paths as above with a different directory structure:

gulp.src(['client/templates/**/*.html'])
  .pipe(domly()) // Compile HTML to document fragment builder functions
  .pipe(declare({
    namespace: 'NS.templates', // Declare within NS.templates
    noRedeclare: true, // Avoid duplicate declarations
    processName: function(filePath) {
      // Drop the client/templates/ folder from the namespace path
      return declare.processNameByPath(filePath.replace('client/templates/', ''));
    }
  })
  .pipe(concat('templates.js'))
  .pipe(gulp.dest('build/js/'));