How to find index of an object by key and value in an javascript array

Question

Given   var peoples          attr1    bob    attr2    pizza          attr1    john    attr2    sushi          attr1    larry    attr2    hummus         Wanted   Index of object where attr     value for example attr1       john  or attr2      hummus   Update  Please  read my question carefully  i do not want to find the object via   inArray nor i want to get the value of a specific object attribute  Please consider this for your answers  Thanks

User · Answer

Do this way -  var peoples          name    bob    dinner    pizza          name    john    dinner    sushi          name    larry    dinner    hummus          each peoples  function i  val          each val  function key  name            if  name      john               alert key           name                 OUTPUT   name   john   Refer LIVE DEMO

User · Answer

The Functional Approach  All the cool kids are doing functional programming  hello React users  these days so I thought I would give the functional solution  In my view it s actually a lot nicer than the imperatival for and each loops that have been proposed thus far and with ES6 syntax it is quite elegant   Update  There s now a great way of doing this called findIndex which takes a function that return true false based on whether the array element matches  as always  check for browser compatibility though    var index   peoples findIndex function person      return person attr1     john      With ES6 syntax you get to write this   var index   peoples findIndex p   gt  p attr1     john       The  Old  Functional Approach  TL DR  If you re looking for index where peoples index  attr1     john  use   var index   peoples map function o    return o attr1     indexOf  john      Explanation  Step 1  Use  map   to get an array of values given a particular key   var values   object array map function o    return o your key        The line above takes you from here   var peoples          attr1    bob    attr2    pizza          attr1    john    attr2    sushi          attr1    larry    attr2    hummus         To here   var values      bob    john    larry       Step 2  Now we just use  indexOf   to find the index of the key we want  which is  of course  also the index of the object we re looking for    var index   values indexOf your value     Solution  We combine all of the above   var index   peoples map function o    return o attr1     indexOf  john      Or  if you prefer ES6 syntax   var index   peoples map  o    gt  o attr1  indexOf  john        Demo    x000D   x000D  var peoples     x000D       attr1    bob    attr2    pizza     x000D       attr1    john    attr2    sushi     x000D       attr1    larry    attr2    hummus    x000D     x000D   x000D  var index   peoples map function o    return o attr1     indexOf  john    x000D  console log  index of  john       index   x000D   x000D  var index   peoples map  o    gt  o attr1  indexOf  larry    x000D  console log  index of  larry       index   x000D   x000D  var index   peoples map function o    return o attr1     indexOf  fred    x000D  console log  index of  fred       index   x000D   x000D  var index   peoples map  o    gt  o attr2  indexOf  pizza    x000D  console log  index of  pizza  in  attr2       index   x000D   x000D   x000D

User · Answer

function getIndexByAttribute list  attr  val       var result   null        each list  function index  item           if item attr  toString      val toString                result   index             return false         breaks the   each   loop                       return result

User · Answer

Using jQuery  each     x000D   x000D  var peoples     x000D       attr1    bob    attr2    pizza     x000D       attr1    john    attr2    sushi     x000D       attr1    larry    attr2    hummus    x000D     x000D   x000D    each peoples  function index  obj    x000D       each obj  function attr  value    x000D        console log  attr            value    x000D         x000D      x000D   lt script src  https   cdnjs cloudflare com ajax libs jquery 3 3 1 jquery min js  gt  lt  script gt  x000D   x000D   x000D    Using for-loop    x000D   x000D  var peoples     x000D       attr1    bob    attr2    pizza     x000D       attr1    john    attr2    sushi     x000D       attr1    larry    attr2    hummus    x000D     x000D   x000D  for  var i   0  i  lt  peoples length  i      x000D    for  var key in peoples i     x000D      console log key            peoples i  key    x000D      x000D    x000D   x000D   x000D

User · Answer

You can also make it a reusable method by expending JavaScript   Array prototype findIndexBy   function key  value        return this findIndex item   gt  item key      value     const peoples     name   john    const cats     id  1  name   kitty     peoples findIndexBy  name    john   cats findIndexBy  id   1

User · Answer

If you want to check on the object itself without interfering with the prototype   use hasOwnProperty     var getIndexIfObjWithOwnAttr   function array  attr  value        for var i   0  i  lt  array length  i              if array i  hasOwnProperty attr   amp  amp  array i  attr      value                return i                      return -1      to also include prototype attributes  use   var getIndexIfObjWithAttr   function array  attr  value        for var i   0  i  lt  array length  i              if array i  attr      value                return i                      return -1

User · Answer

Not a direct answer to your question  though I thing it s worth mentioning it  because your question seems like fitting in the general case of  getting things by name in a key-value storage    If you are not tight to the way  peoples  is implemented  a more JavaScript-ish way of getting the right guy might be    var peoples        bob       dinner    pizza        john      dinner    sushi        larry     dinner    hummus           If people is implemented this way  then    you can get values from their name  like   var theGuy   peoples  john        You can event get directly to the values var thatGuysPrefferedDinner   peoples  john   dinner    Hope if this is not the answer you wanted  it might help people interested in that  key value  question

[javascript] How to find index of an object by key and value in an javascript array

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