Mixin Catalog

This page serves to catalog shared underscore mixins, here and elsewhere.

Background: Mixin Syntax

_.mixin(object)

Allows you to extend Underscore with your own utility functions. Pass a hash of {name: function} definitions to have your functions added to the Underscore object, as well as the OOP wrapper.

_.mixin({
  capitalize : function(string) {
    return string.charAt(0).toUpperCase() + string.substring(1).toLowerCase();
  }
});
_("fabio").capitalize();
=> "Fabio"

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Strings

• Esa-Matti Suuronen has a sweet git repo named underscore.string which adds many string functions to Underscore.js through mixins.

• Jos de Jong created a mixin interpolate, which substitutes properties in a string, for example: _var msg = _interpolate('Hello, $name!', {name: 'Jos'})

• levenshteinDistance – count edits required to turn one string into another

Misc Mixins in the Wild

(update me!)

• (newest) Ben Sisson, “underscore-join” adds a function similar to SQL Joins https://github.com/bensisson/underscore-join

• Andrea Puddu, squeeze – or JSON extract/flatten – Returns an array with only the string values of the given object (any depth).

• David Beck, underscore-template-helpers is a mixin that allows you to define global helper functions that will always be available in your underscore templates.

• furf, underscore.js mixin for plucking nested properties is a gist with three mixins: deep.js to get/set the value of a nested property, pluckdeep.js which returns deeply nested values, and unpick.js which returns a copy of an object containing all but the blacklisted properties.

• Eddie Anderson, findKeysByValue.js Find object keys for a given value.

• Mike Jones, Underscore.altWhere Extends the _.where concept to return object members based on a choice of values in a key:value pair.

• Elliot Chong, underscore.deepExtend allows you to deeply combine two or more objects that share common object keys. Useful for combining complex hashmaps, such as: _.deepExtend({ "name": { "first": "Earl" }, "job": "Mad Scientist" }, { "name": { "last": "Duncan" }}); results in { "name": { "first": "Earl", "last": "Duncan" }, "job": "Mad Scientist" }

• Sam Breed, underscore.deferred implements jQuery-like deferreds in Underscore.

• Matt Mueller, Underscore Extension: Observer Pattern is a set of four Node-like methods – _.on, _.once, _.emit, and _.removeEvent.

• Oleg Slobodskoi (@oleg008) nodejs style _.inherits method using Object.create and fallback to cloning via prototype

• Tim Wood created a mixin called Moment.js (originally “underscore.date”) that parses, validates, manipulates, and displays dates.

• Omar Yasin published a mixin in this gist that provides a ‘printf’-like functionality

• Xavier Spriet has this gist that has a mixin to emulate ruby’s Array#each_slice method.

• Francesco Agati provides this gist with _.selectIf

• Steven Black, in this gist _.filterObj: Return an object who’s members are culled to match a reference array of keys.

• Vladimir Dronnikov: object helpers _.freeze, _.proxy, _.get

• Vladimir Dronnikov: Practical JSON-schema validator

• Vladimir Dronnikov: Query Language For Arrays/Hashes

• thegrandpoobah suggests this _.retry mixin.

• OnesimusUnbound: counter and cycle generator mixin

• Marçal Juan: compact function for Objects mixin

• Mario T. Lanza: Roll your own objects using not just dynamic values, but dynamic keys.

• Arnau Sanchez: Mixins: merge, mash, takeWhile, mapDetect, uniqWith, flatten1.

• Adrian Lang: _.mapValues mapping Objects to Objects

• Paul Harper (benekastah): underscore.loop – adds scheme/clojure like recursive looping with tail-call optimization.

• Kevin Malakoff (kmalakoff): underscore-awesomer – many “awesome” functions like ‘toJSON’/‘parseJSON’ for instance serializaion/deserializaion, ‘compare’, ‘keypath’ for accessing nested properties, ‘remove’, ‘own’/‘disown’, ‘cloneToDepth’, ‘toType’ conversions using to{X} function as a fallback if the types don’t match, etc.

• Julian Burgess (aubergene): _.rotate – Array rotate mixin

• Trevor Parscal (trevorparscal): more-underscore – More stuff for underscore, such as ‘extendClass’ (prototypical inheritance), ‘objectify’ (combine array values with property names) and ‘traverse’ (get a value from a multi-level collection using an array of keys and indexes).

• tobias104 provides this _.indexBy gist – Combination of _.find and _.indexOf, that returns the index of the first item that passes the test.

• Mark Rushakoff (mark-rushakoff): function binding helpers – provides two functions similar to _.bindAll. _.bindFiltered takes a filter function that operates on function names, and _.bindMatching takes a regex for the names of which functions to bind.

• Adrian Rossouw (Vertice): Partial function application binders – provides a function called _.partial which allows you to bind specific arguments, leaving a closure. Also contains a _.wrapAsync, which turns non-async calls into the format node.js expects. _.partialAsync does both.

• Andreas Briese (AndreasBriese): Addon functions sum, mean, median and nrange (~enhanced range)

• Simon Kågedal Reimer (skagedal): underscore-pickrandom.js — provides a function, _.pickRandom(array, [n]) that picks random elements from an array. It works similar to _.first(_.shuffle(array, n)), but is more efficient; it operates in time proportional to n rather than the length of the whole array.

• Tony Stuck (toekneestuck): underscore.nl2br – A simple port of nl2br to Underscore for string manipulation.

• Ross Cairns (rc1): body – provides the middle/body of an Array.

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Discussion

This page is a bit hard to browse and quickly find what you need. I’d suggest: 1. group mixins by functionality; 2. emphasize what functions each mixin provides with a short description for each function (more like the underscore main page); 3. put less emphasis on the author. /skagedal (sorry if this isn’t the proper way of discussing wiki pages)