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This library is a collection of helpful methods and monkey patches for Arrays, Objects, Numbers, and Strings in Javascript. Start writing your Javascript like you write your Ruby code!

Works in the Browser and in NodeJS.

5.1kb minified and gzipped.


Yarn, NPM, Bower

yarn add rearmed-js

npm install rearmed-js

bower install rearmed-js

Rails / Bundler

# Gemfile
source '' do
  gem 'rails-assets-rearmed-js'


Note: Only import/require the patches once at the beginning of your page or app start otherwise you will get warnings about redefining methods.

Plain HTML

<script src="rearmed-js/dist/rearmed.min.js" type="text/javascript" />

<!-- OR only the patches you want -->

<!-- All patches for a certain object type only -->
<script src="rearmed-js/dist/array.min.js" type="text/javascript" />
<script src="rearmed-js/dist/number.min.js" type="text/javascript" />
<script src="rearmed-js/dist/object.min.js" type="text/javascript" />
<script src="rearmed-js/dist/string.min.js" type="text/javascript" />
<script src="rearmed-js/dist/generic.min.js" type="text/javascript" />

<!-- OR only the methods you want -->
<script src="rearmed-js/dist/array/reject.min.js" type="text/javascript" />
<script src="rearmed-js/dist/array/select.min.js" type="text/javascript" />


import 'rearmed-js'; // import everything

// OR 

// import patches for certain object types only
import 'rearmed-js/array';
import 'rearmed-js/number';
import 'rearmed-js/object';
import 'rearmed-js/string';
import 'rearmed-js/generic';

// OR

// import only the methods you want
import 'rearmed-js/array/reject';
import 'rearmed-js/array/select';


require('rearmed-js') // require everything

// OR

// require patches for certain object types only

// OR

// require only the methods you want


 *= require rearmed-js
 * OR for certain object types only
 *= require rearmed-js/array
 *= require rearmed-js/number
 *= require rearmed-js/object
 *= require rearmed-js/string
 *= require rearmed-js/generic
 * OR only the methods you want
 *= require rearmed-js/array/reject
 *= require rearmed-js/array/select

Methods Implemented


These methods are available on all types that inherit from Object which is almost everything.

var cb = function(){ };
var str = "";
var array = [];

str.equals(array); // returns bool

str.isBlank(); // returns bool
// collections are blank if length == 0

str.isPresent(); // return bool
// collections are present if length > 0

array.presence(); // returns self or false
// same thing as: array.isPresent() ? array : false;

cb.simpleType(); // return str
// possible return values are 'Object','Array','String','Boolean','Number','Function','Other'

// return value or false
str.try('length'); // => 0
array.try('sort'); // => []
str.try('badMethod').try('anotherBadMethod'); // => false


var array = [];

var cb = function(val, i){ };

array.any(cb=null) // returns bool

array.all(cb=null) // returns bool

array.compact(badValues=[null, undefined, '']) // returns array, accepts array or splat arguments
array.dig(*args) // returns value, accepts splat arguments or array

array.each(function(val, i){ })

array.empty() // return bool

array.equals(array) // returns bool

array.excludes(val, fromIndex=0) //  returns bool

array.find(cb_or_val) // returns value, undefined if not found

array.findIndex(cb_or_val) // returns integer, undefined if not found

array.first() // returns value

array.flatten() // returns array

array.includes(val, fromIndex=0) // returns bool

array.inGroupsOf(int, fillWith=false) // returns nested array

array.groupBy(cb) // returns nested array

array.last // returns value

array.max(cb=null) // returns value

array.maxBy(cb=null) // returns value

array.min(cb=null) // returns value

array.minBy(cb=null) // returns value

array.reject(cb) // reutrns array // returns array

array.tap(cb); // returns array
// this is an each method that returns the original array after its done

array.smartIncludes(val, fromIndex=0) // returns bool
// smart meaning that it uses `equals` method to compare if item is Array or Object

array.smartExcludes(val, fromIndex=0) // returns bool
// smart meaning that it uses `equals` method to compare if item is Array or Object

array.sum(cb=null) // returns number

array.uniq(cb=null) // returns array

/* CLASS METHODS - Not available in Typescript */

Array.range(startNumber, endNumber, step=1) // returns array

Object (Hash)

var obj = {};

// Monkey-patching Object is very dangerous, so we only patch it with one method
obj = obj.rearmed(); 

var cb = function(key, val){ };

obj.all(cb=null) // returns bool

obj.any(cb=null) // returns bool

obj.compact(badValues=[null, undefined, '']) // returns object, accepts array or splat arguments

obj.dig(*args) // returns object, accepts splat arguments or array


obj.empty() // returns bool

obj.equals(obj) // returns bool

obj.except(*keys) // returns object, accepts keys as splat arguments or an array

obj.hasKey() // returns bool

obj.hasValue() // returns bool

obj.join(cb, delimiter=', ') // returns string

obj.keys() // returns array

obj.merge(obj) // returns object

obj.only(*keys) // returns object, accepts keys as splat arguments or an array

obj.reject(cb) // returns object // returns object, known to cause error with React select elements

obj.values() // returns array

When requiring Object patches individually you must first require object/rearmed. Example:


The following methods are used under the hood to provide patches to Object. I have exposed these methods publicly so that you can add your own custom methods to rearmed() objects. These methods are available on Object after requiring either of these: rearmed-js/object/rearmed or rearmed-js

  myMethodName: function(){
    // add new method to rearmed() objects

  myMethodName: function(){
    // remove method from rearmed() objects


var num = 8.5;

num.ceil() // returns number

num.floor() // returns number

num.isDecimal() // returns bool

num.isEven() // returns bool

num.isInteger() // returns bool

num.isOdd() // returns bool

num.round() // returns number


var str = 'Hello World':

str.capitalize() // returns string

str.caseCmp(str) // returns bool

str.chars() // returns array

str.downcase() // returns string

str.empty() // returns bool

str.endsWith(val) // returns bool

str.excludes(val, fromIndex=0) // returns bool

str.gsub(str, toStr) // returns string

str.includes(val, fromIndex=0) // returns bool

str.lstrip() // returns string

str.reverse() // returns string

str.rstrip() // returns string

str.startsWith(val) // returns bool

str.strip() // returns string

str.sub(str, toStr) // returns string
// Warning: doesn't warn when it overwrites the original sub method as it has been removed from the JS standard.

str.titleize(onlyFirstLetters=true) // returns string

str.toBool() // returns bool

str.upcase() // returns string

Browser / NodeJS / Typescript Support

  • Browser support is IE 9+ and everything else. Use the files in the dist folder if you need pre-minified files.
  • Array find doesnt work properly in old NodeJS 0.x and iojs.
  • String empty doesnt work properly in old NodeJS 0.x.
  • Typescript is supported however it does not support Class methods because its not possible to define static methods on existing interfaces such as Array. At this time the only effected method is Array.range


  • I recommend discussing your intentions via an issue before making a PR because there are very concious design choices that must go into this library.
  • Only edit js files from src/ and test/ folders.
  • Use the gulp task: gulp to run the build after making your changes.
  • PR's should include tests. Testing these methods are simple & easy, check the test folder to see how it works.


Created by Weston Ganger - @westonganger

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A collection of helpful methods and monkey patches for Arrays, Objects, Numbers, and Strings in Javascript








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