jQuery function to get all unique elements from an array

Question

jQuery unique lets you get unique elements of an array  but the docs say the function is mostly for internal use and only operates on DOM elements  Another SO response said the unique   function worked on numbers  but that this use case is not necessarily future proof because it s not explicitly stated in the docs   Given this  is there a  standard  jQuery function for accessing only the unique values     specifically  primitives like integers     in an array   Obviously  we can construct a loop with the each   function  but we are new to jQuery and would like to know if there is a dedicated jQuery function for this

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Paul Irish has a  Duck Punching  method  see example 2  that modifies jQuery s   unique   method to return unique elements of any type    function         var  old     unique        unique   function arr              do the default behavior only if we got an array of elements         if    arr 0  nodeType               return  old apply this arguments             else                  reduce the array to contain no dupes via grep inArray             return   grep arr function v k                   return   inArray v arr      k                                      jQuery

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Just use this code as the basis of a simple JQuery plugin     extend       distinct   function anArray           var result                each anArray  function i v              if    inArray v  result     -1  result push v                     return result              Use as so     distinct  0 1 2 2 3

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Walk the array and push items into a hash as you come across them   Cross-reference the hash for each new element   Note that this will ONLY work properly for primitives  strings  numbers  null  undefined  NaN  and a few objects that serialize to the same thing  functions  strings  dates  possibly arrays depending on content    Hashes in this will collide as they all serialize to the same thing  e g    object Object    Array prototype distinct   function       var map       out           for var i 0  l this length  i lt l  i           if map this i     continue           out push this i          map this i     1           return out      There s also no reason you can t use jQuery unique   The only thing I don t like about it is that it destroys the ordering of your array   Here s the exact code for it if you re interested   Sizzle uniqueSort   function results       if   sortOrder             hasDuplicate   baseHasDuplicate          results sort sortOrder            if   hasDuplicate                 for   var i   1  i  lt  results length  i                       if   results i      results i-1                          results splice i--  1                                                        return results

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If you need to support IE 8 or earlier  you can use jQuery to accomplish this   var a    1 2 2 3 4 3 5   var unique     grep a  function  item  index       return index       inArray item  a

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function array unique array        var unique           for   var i   0   i  lt  array length     i             if   unique indexOf array i      -1               unique push array i              return unique

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You can use a jQuery plugin called Array Utilities to get an array of unique items  It can be done like this   var distinctArray     distinct  1  2  2  3     distinctArray    1 2 3

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this is js1568 s solution  modified to work on a generic array of objects  like    var genericObject            genProp  this is a string  randomInt 10 isBoolean false            genProp  this is another string  randomInt 20 isBoolean false            genProp  this is a string  randomInt 10 isBoolean true            genProp  this is another string  randomInt 30 isBoolean false            genProp  this is a string  randomInt 40 isBoolean true            genProp  i like strings  randomInt 60 isBoolean true            genProp  this is a string  randomInt 70 isBoolean true            genProp  this string is unique  randomInt 50 isBoolean true            genProp  this is a string  randomInt 50 isBoolean false            genProp  i like strings  randomInt 70 isBoolean false          It accepts one more parameter called propertyName  guess          extend           distinctObj function obj propertyName                var result                     each obj function i v                   var prop eval  v   propertyName                   if    inArray prop  result     -1  result push prop                               return result                      so  if you need to extract a list of unique values for a given property  for example the values used for randomInt property  use this     distinctObj genericObject  genProp      it returns an array like this     this is a string    this is another string    i like strings    this string is unique

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Plain JavaScript modern solution if you don t need IE support  Array from is not supported in IE    You can use combination of Set and Array from    x000D   x000D  const arr    1  1  11  2  4  2  5  3  1   x000D  const set   new Set arr   x000D  const uniqueArr   Array from set   x000D   x000D  console log uniqueArr   x000D   x000D   x000D    The Set object lets you store unique values of any type  whether primitive values or object references   The Array from   method creates a new Array instance from an array-like or iterable object   Also Array from   can be replaced with spread operator    x000D   x000D  const arr    1  1  11  2  4  2  5  3  1   x000D  const set   new Set arr   x000D  const uniqueArr       set   x000D   x000D  console log uniqueArr   x000D   x000D   x000D

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As of jquery 3 0 you can use   uniqueSort ARRAY   Example  array     1   2   1   2     uniqueSort array    gt    1    2

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for numbers     a    1 3 2 4 5 6 7 8  1 1 4 5 6        unique a       7  6  1  8  3  2  5  4          for string     a     a    a    b         unique a        b    a     And for dom elements there is no example is needed here I guess because you already know that   Here is the jsfiddle link of live example  http   jsfiddle net 3BtMc 4

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If anyone is using knockoutjs try   ko utils arrayGetDistinctValues     BTW have look at all ko utils array  utilities

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Based on  kennebec s answer  but fixed for IE8 and below by using jQuery wrappers around the array to provide missing Array functions filter and indexOf     makeArray   wrapper might not be absolutely needed  but you ll get odd results if you omit this wrapper and JSON stringify the result otherwise   var a    1 5 1 6 4 5 2 5 4 3 1 2 6 6 3 3 2 4       note  jQuery s filter params are opposite of javascript s native implementation    var unique     makeArray   a  filter function i itm           note   index   not  indexOf      return i      a  index itm            unique   1  5  6  4  2  3

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You can use array filter to return the first item of each distinct value-   x000D   x000D  var a     1  5  1  6  4  5  2  5  4  3  1  2  6  6  3  3  2  4    x000D   x000D  var unique   a filter function itm  i  a    x000D      return i    a indexOf itm   x000D      x000D   x000D  console log unique   x000D   x000D   x000D    If supporting IE8 and below is primary  don t use the unsupported filter method    Otherwise   if   Array prototype filter        Array prototype filter   function fun  scope            var T   this  A       i   0  itm  L   T length          if  typeof fun     function                 while i  lt  L                    if  i in T                        itm   T i                       if  fun call scope  itm  i  T   A A length    itm                                      i                                  return A

User · Answer

I would use underscore js  which provides  a uniq method that does what you want

[javascript] jQuery function to get all unique elements from an array?

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