Miscellaneous utilities for your Gruntfile and tasks.


Return the "kind" of a value. Like typeof but returns the internal [Class](Class/) value. Possible results are "number", "string", "boolean", "function", "regexp", "array", "date", "error", "null", "undefined" and the catch-all "object".



Return a new Error instance (that can be thrown) with the appropriate message. If an Error object is specified instead of message that object will be returned. Also, if an Error object is specified for origError and Grunt was run with the --stack option, the original Error stack will be dumped.

grunt.util.error(message [, origError])


The linefeed character, normalized for the current operating system. (\r\n on Windows, \n otherwise)


Given a string, return a new string with all the linefeeds normalized for the current operating system. (\r\n on Windows, \n otherwise)



Recurse through nested objects and arrays, executing callbackFunction for each non-object value. If continueFunction returns false, a given object or value will be skipped.

grunt.util.recurse(object, callbackFunction, continueFunction)


Return string str repeated n times.

grunt.util.repeat(n, str)


Given str of "a/b", If n is 1, return "a" otherwise "b". You can specify a custom separator if '/' doesn't work for you.

grunt.util.pluralize(n, str, separator)


Spawn a child process, keeping track of its stdout, stderr and exit code. The method returns a reference to the spawned child. When the child exits, the doneFunction is called.

grunt.util.spawn(options, doneFunction)

The options object has these possible properties:

var options = {
  // The command to execute. It should be in the system path.
  cmd: commandToExecute,
  // If specified, the same grunt bin that is currently running will be
  // spawned as the child command, instead of the "cmd" option. Defaults
  // to false.
  grunt: boolean,
  // An array of arguments to pass to the command.
  args: arrayOfArguments,
  // Additional options for the Node.js child_process spawn method.
  opts: nodeSpawnOptions,
  // If this value is set and an error occurs, it will be used as the value
  // and null will be passed as the error value.
  fallback: fallbackValue

The doneFunction accepts these arguments:

function doneFunction(error, result, code) {
  // If the exit code was non-zero and a fallback wasn't specified, an Error
  // object, otherwise null.
  // The result object is an object with the properties .stdout, .stderr, and
  // .code (exit code).
  // When result is coerced to a string, the value is stdout if the exit code
  // was zero, the fallback if the exit code was non-zero and a fallback was
  // specified, or stderr if the exit code was non-zero and a fallback was
  // not specified.
  // The numeric exit code.


Given an array or array-like object, return an array. Great for converting arguments objects into arrays.



Normalizes both "returns a value" and "passes result to a callback" functions to always pass a result to the specified callback. If the original function returns a value, that value will now be passed to the callback, which is specified as the last argument, after all other predefined arguments. If the original function passed a value to a callback, it will continue to do so.


This example might better illustrate:

function add1(a, b) {
  return a + b;
function add2(a, b, callback) {
  callback(a + b);

var fn1 = grunt.util.callbackify(add1);
var fn2 = grunt.util.callbackify(add2);

fn1(1, 2, function(result) {
  console.log('1 plus 2 equals ' + result);
fn2(1, 2, function(result) {
  console.log('1 plus 2 equals ' + result);

Internal libraries


An internal library for resolving deeply-nested properties in objects.


An internal library for task running.

External libraries


All external libraries that are listed below are now deprecated.

Please use npm to manage these external libraries in your project's dependencies.

For example if you want to use Lo-Dash, install it first: npm install lodash, then use it in your Gruntfile: var _ = require('lodash');.



Lo-Dash and Underscore.string

grunt.util._.str is available for methods that conflict with existing Lo-Dash methods.



Async - Async utilities for node and the browser.



JavaScript Hooker - Monkey-patch (hook) functions for debugging and stuff.