grunt-contrib-concat
Advanced tools
The grunt-contrib-concat package is a Grunt plugin used to concatenate files. It is commonly used in build processes to combine multiple files into a single file, which can help reduce the number of HTTP requests and improve load times for web applications.
Concatenate JavaScript files
This feature allows you to concatenate multiple JavaScript files into a single file. The 'separator' option specifies the string to use between each file in the concatenated output.
{
"concat": {
"options": {
"separator": ";\n"
},
"dist": {
"src": ["src/js/file1.js", "src/js/file2.js"],
"dest": "dist/js/bundle.js"
}
}
}Concatenate CSS files
This feature allows you to concatenate multiple CSS files into a single file. This can be useful for reducing the number of CSS files that need to be loaded by the browser.
{
"concat": {
"css": {
"src": ["src/css/style1.css", "src/css/style2.css"],
"dest": "dist/css/styles.css"
}
}
}Custom banner and footer
This feature allows you to add a custom banner at the beginning and a footer at the end of the concatenated file. This can be useful for adding comments or metadata to the output file.
{
"concat": {
"options": {
"banner": "/* My Project - concatenated on <%= grunt.template.today('yyyy-mm-dd') %> */\n",
"footer": "\n/* End of concatenated files */"
},
"dist": {
"src": ["src/js/file1.js", "src/js/file2.js"],
"dest": "dist/js/bundle.js"
}
}
}gulp-concat is a Gulp plugin that concatenates files. It is similar to grunt-contrib-concat but is used within the Gulp task runner ecosystem. Gulp's streaming build system can be more flexible and faster for certain tasks compared to Grunt.
broccoli-concat is a Broccoli plugin for concatenating files. It is used within the Broccoli build tool, which is known for its fast rebuild times and efficient file watching. This makes it a good alternative for projects that use Broccoli instead of Grunt.
webpack-concat-plugin is a Webpack plugin that concatenates files. It integrates with Webpack's module bundling system, making it a good choice for projects that use Webpack for their build process. It offers more advanced features like dependency resolution and code splitting.
Concatenate files.
If you haven't used Grunt before, be sure to check out the Getting Started guide, as it explains how to create a Gruntfile as well as install and use Grunt plugins. Once you're familiar with that process, you may install this plugin with this command:
npm install grunt-contrib-concat --save-dev
Once the plugin has been installed, it may be enabled inside your Gruntfile with this line of JavaScript:
grunt.loadNpmTasks('grunt-contrib-concat');
Run this task with the grunt concat command.
Task targets, files and options may be specified according to the Grunt Configuring tasks guide.
Type: String
Default: grunt.util.linefeed
Concatenated files will be joined on this string. If you're post-processing concatenated JavaScript files with a minifier, you may need to use a semicolon ';\n' as the separator.
Type: String
Default: ''
This string will be prepended to the beginning of the concatenated output. It is processed using grunt.template.process, using the default options.
(Default processing options are explained in the grunt.template.process documentation)
Type: String
Default: ''
This string will be appended to the end of the concatenated output. It is processed using grunt.template.process, using the default options.
(Default processing options are explained in the grunt.template.process documentation)
Type: Boolean Object
Default: false
Strip JavaScript banner comments from source files.
false - No comments are stripped.true - /* ... */ block comments are stripped, but NOT /*! ... */ comments.options object:
true were specified.block - If true, all block comments are stripped.line - If true, any contiguous leading // line comments are stripped.Type: Boolean Object Function
Default: false
Process source files before concatenating, either as templates or with a custom function.
false - No processing will occur.true - Process source files using grunt.template.process defaults.data object - Process source files using grunt.template.process, using the specified options.function(src, filepath) - Process source files using the given function, called once for each file. The returned value will be used as source code.(Default processing options are explained in the grunt.template.process documentation)
Type: Boolean
Default: false
Set to true to create a source map. The source map will be created alongside the destination file, and share the same file name with the .map extension appended to it.
Type: String Function
Default: undefined
To customize the name or location of the generated source map, pass a string to indicate where to write the source map to. If a function is provided, the concat destination is passed as the argument and the return value will be used as the file name.
Type: String
Default: embed
Determines the type of source map that is generated. The default value, embed, places the content of the sources directly into the map. link will reference the original sources in the map as links. inline will store the entire map as a data URI in the destination file.
In this example, running grunt concat:dist (or grunt concat because concat is a multi task) will concatenate the three specified source files (in order), joining files with ; and writing the output to dist/built.js.
// Project configuration.
grunt.initConfig({
concat: {
options: {
separator: ';',
},
dist: {
src: ['src/intro.js', 'src/project.js', 'src/outro.js'],
dest: 'dist/built.js',
},
},
});
In this example, running grunt concat:dist will first strip any preexisting banner comment from the src/project.js file, then concatenate the result with a newly-generated banner comment, writing the output to dist/built.js.
This generated banner will be the contents of the banner template string interpolated with the config object. In this case, those properties are the values imported from the package.json file (which are available via the pkg config property) plus today's date.
Note: you don't have to use an external JSON file. It's also valid to create the pkg object inline in the config. That being said, if you already have a JSON file, you might as well reference it.
// Project configuration.
grunt.initConfig({
pkg: grunt.file.readJSON('package.json'),
concat: {
options: {
stripBanners: true,
banner: '/*! <%= pkg.name %> - v<%= pkg.version %> - ' +
'<%= grunt.template.today("yyyy-mm-dd") %> */',
},
dist: {
src: ['src/project.js'],
dest: 'dist/built.js',
},
},
});
In this example, running grunt concat will build two separate files. One "basic" version, with the main file essentially just copied to dist/basic.js, and another "with_extras" concatenated version written to dist/with_extras.js.
While each concat target can be built individually by running grunt concat:basic or grunt concat:extras, running grunt concat will build all concat targets. This is because concat is a multi task.
// Project configuration.
grunt.initConfig({
concat: {
basic: {
src: ['src/main.js'],
dest: 'dist/basic.js',
},
extras: {
src: ['src/main.js', 'src/extras.js'],
dest: 'dist/with_extras.js',
},
},
});
Like the previous example, in this example running grunt concat will build two separate files. One "basic" version, with the main file essentially just copied to dist/basic.js, and another "with_extras" concatenated version written to dist/with_extras.js.
This example differs in that both files are built under the same target.
Using the files object, you can have list any number of source-destination pairs.
// Project configuration.
grunt.initConfig({
concat: {
basic_and_extras: {
files: {
'dist/basic.js': ['src/main.js'],
'dist/with_extras.js': ['src/main.js', 'src/extras.js'],
},
},
},
});
Filenames can be generated dynamically by using <%= %> delimited underscore templates as filenames.
In this example, running grunt concat:dist generates a destination file whose name is generated from the name and version properties of the referenced package.json file (via the pkg config property).
// Project configuration.
grunt.initConfig({
pkg: grunt.file.readJSON('package.json'),
concat: {
dist: {
src: ['src/main.js'],
dest: 'dist/<%= pkg.name %>-<%= pkg.version %>.js',
},
},
});
In this more involved example, running grunt concat will build two separate files (because concat is a multi task). The destination file paths will be expanded dynamically based on the specified templates, recursively if necessary.
For example, if the package.json file contained {"name": "awesome", "version": "1.0.0"}, the files dist/awesome/1.0.0/basic.js and dist/awesome/1.0.0/with_extras.js would be generated.
// Project configuration.
grunt.initConfig({
pkg: grunt.file.readJSON('package.json'),
dirs: {
src: 'src/files',
dest: 'dist/<%= pkg.name %>/<%= pkg.version %>',
},
concat: {
basic: {
src: ['<%= dirs.src %>/main.js'],
dest: '<%= dirs.dest %>/basic.js',
},
extras: {
src: ['<%= dirs.src %>/main.js', '<%= dirs.src %>/extras.js'],
dest: '<%= dirs.dest %>/with_extras.js',
},
},
});
If you would like the concat task to warn if a given file is missing or invalid be sure to set nonull to true:
grunt.initConfig({
concat: {
missing: {
src: ['src/invalid_or_missing_file'],
dest: 'compiled.js',
nonull: true,
},
},
});
See configuring files for a task for how to configure file globbing in Grunt.
If you would like to do any custom processing before concatenating, use a custom process function:
grunt.initConfig({
concat: {
dist: {
options: {
// Replace all 'use strict' statements in the code with a single one at the top
banner: "'use strict';\n",
process: function(src, filepath) {
return '// Source: ' + filepath + '\n' +
src.replace(/(^|\n)[ \t]*('use strict'|"use strict");?\s*/g, '$1');
},
},
files: {
'dist/built.js': ['src/project.js'],
},
},
},
});
charset:utf-8 to sourceMappingURL.sourceMap option.this.files API.this.file API internally.Task submitted by "Cowboy" Ben Alman
This file was generated on Sun Apr 03 2022 07:55:57.
FAQs
Concatenate files.
We found that grunt-contrib-concat demonstrated a not healthy version release cadence and project activity because the last version was released a year ago. It has 6 open source maintainers collaborating on the project.
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