Jquery how to find an Object by attribute in an Array

Question

Given I have an array of  purpose  objects     array of purpose objects  var purposeObjects          purpose   daily         purpose   weekly         purpose   monthly         for simplicity i am omitting other attributes   Now I want to have a method that returns a specific one of the objects if a matching purpose name is found    This is not working   function findPurpose purposeName       return   grep purposeObjects  function          return this purpose    purposeName              findPurpose  daily      but it actually returns an empty array        I am using JQuery 1 5 2  I have also tried with   each   but with no luck   Apparently  most JQuery methods are designed for usage with DOM elements  such as filter      Any ideas on how to achieve this

User · Answer

Use the Underscore js findWhere function  http   underscorejs org  findWhere    var purposeObjects          purpose   daily         purpose   weekly         purpose   monthly       var daily     findWhere purposeObjects   purpose   daily       daily would equal     purpose   daily     Here s a fiddle  http   jsfiddle net spencerw oqbgc21x   To return more than one  if you had more in your array  you could use   where

User · Answer

The error was that you cannot use this in the grep  but you must use a reference to the element  This works   function findPurpose purposeName       return   grep purposeObjects  function n  i         return n purpose    purposeName              findPurpose  daily      returns     Object   purpose  daily

User · Answer

you should pass reference on item in grep function   function findPurpose purposeName       return   grep purposeObjects  function item         return item purpose    purposeName               Example

User · Answer

Best  Fastest way is  function arrayLookup array  prop  val        for  var i   0  len   array length  i  lt  len  i              if  array i  hasOwnProperty prop   amp  amp  array i  prop      val                return array i                       return null

User · Answer

I personally use a more generic function that works for any property of any array   function lookup array  prop  value        for  var i   0  len   array length  i  lt  len  i            if  array i   amp  amp  array i  prop      value  return array i       You just call it like this   lookup purposeObjects   purpose    daily

User · Answer

Javascript has a function just for that  Array prototype find  As example  function isBigEnough element      return element  gt   15      12  5  8  130  44  find isBigEnough      130   It not difficult to extends the callback to a function  However this is not compatible with IE  and partially with Edge   For a full list look at the Browser Compatibility

User · Answer

No need for jQuery  JavaScript arrays have a find method  so you can achieve that in one line  array find  o    gt    return o propertyName      propertyValue    Example  const purposeObjects          purpose   quot daily quot         purpose   quot weekly quot         purpose   quot monthly quot       purposeObjects find  o    gt    return o  quot purpose quot        quot weekly quot        output - gt   purpose   quot weekly quot    If you need IE compatibility  import this polyfill in your code

User · Answer

copied from polyfill Array prototype find code of Array find  and added the array as first parameter   you can pass the search term as predicate function   x000D   x000D     Example x000D  var listOfObjects     key   1   value   one     key   2   value   two    x000D  var result   findInArray listOfObjects  function element    x000D    return element key     1   x000D      x000D  console log result   x000D   x000D     the function you want x000D  function findInArray listOfObjects  predicate    x000D        if  listOfObjects    null    x000D          throw new TypeError  listOfObjects is null or not defined    x000D          x000D   x000D        var o   Object listOfObjects   x000D   x000D        var len   o length  gt  gt  gt  0  x000D   x000D        if  typeof predicate      function     x000D          throw new TypeError  predicate must be a function    x000D          x000D   x000D        var thisArg   arguments 1   x000D   x000D        var k   0  x000D   x000D        while  k  lt  len    x000D          var kValue   o k   x000D          if  predicate call thisArg  kValue  k  o     x000D            return kValue  x000D            x000D          k    x000D          x000D   x000D        return undefined  x000D    x000D   x000D   x000D

User · Answer

I have created a util service for my angular application  It have two function which use very often    For example you have object   First getting value from object recursively without throwing undefined error    prop    nestedProp1   nestedProp2  somevalue      get nestedProp2 2 without undefined checks   Second filter array on basis     prop    nestedProp1   nestedProp2  somevalue1      prop    nestedProp1   nestedProp2  somevalue2        Find object from array with nestedProp2 somevalue2  app service  UtilService   function httpService    this mapStringKeyVal   function map  field        var lastIdentifiedVal   null      var parentVal   map      field split      forEach function val           if parentVal val                lastIdentifiedVal   parentVal val                parentVal   parentVal val                          return lastIdentifiedVal      this arrayPropFilter   function array  field value        var lastIdentifiedVal   null      var mapStringKeyVal   this mapStringKeyVal      array forEach function arrayItem           var valueFound   mapStringKeyVal arrayItem field           if  lastIdentifiedVal   amp  amp  valueFound  amp  amp  valueFound  value               lastIdentifiedVal   arrayItem                        return lastIdentifiedVal         For solution for current question  inject UtilService and call   UtilService arrayPropFilter purposeArray  purpose   daily      Or more advanced  UtilService arrayPropFilter purposeArray  purpose nestedProp1 nestedProp2   daily

User · Answer

If your array is actually a set of JQuery objects  what about simply using the  filter   method    purposeObjects filter   purpose  daily

User · Answer

One more solution   function firstOrNull array  expr      for  var i   0  i  lt  array length  i          if  expr array i          return array i           return null      Using  firstOrNull    a  1  b  2      a  3  b  3     function item    return item a     3       This function don t executes for each element from the array  it s valuable for large arrays

[jquery] Jquery how to find an Object by attribute in an Array

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