get one item from an array of name value JSON

Question

I have this array   var arr       arr push  name  k1   value  abc     arr push  name  k2   value  hi     arr push  name  k3   value  oa       is it possible to do get the value or a specific element by knowing the name    something like this   arr  k2   value   or   arr get  k1

User · Answer

To answer your exact question you can get the exact behaviour you want by extending the Array prototype with:

Array.prototype.get = function(name) {
    for (var i=0, len=this.length; i<len; i++) {
        if (typeof this[i] != "object") continue;
        if (this[i].name === name) return this[i].value;
    }
};

this will add the get() method to all arrays and let you do what you want, i.e:

arr.get('k1'); //= abc

User · Answer

The easiest approach which I have used is   var found   arr find function element             return element name      k1           If you print the found   console log found     gt  Object   name   k1   value   abc       If you need the value console log found value    gt   abc    The similar approach can be used to find the values from the JSON Array based on any input data from the JSON

User · Answer

Arrays are normally accessed via numeric indexes  so in your example arr 0      name  k1   value  abc    If you know that the name property of each object will be unique you can store them in an object instead of an array  as follows   var obj       obj  k1      abc   obj  k2      hi   obj  k3      oa    alert obj  k2        displays  hi    If you actually want an array of objects like in your post you can loop through the array and return when you find an element with an object having the property you want   function findElement arr  propName  propValue      for  var i 0  i  lt  arr length  i        if  arr i  propName     propValue        return arr i         will return undefined if not found  you could return a default instead       Using the array from the question var x   findElement arr   name    k2       x is   name   k2    value   hi   alert x  value        displays  hi   var y   findElement arr   name    k9       y is undefined alert y  value        error because y is undefined  alert findElement arr   name    k2    value        displays  hi    alert findElement arr   name    zzz    value        gives an error because the function returned undefined which won t have a  value  property

User · Answer

I don t know anything about jquery so can t help you with that  but as far as Javascript is concerned you have an array of objects  so what you will only be able to access the names  amp  values through each array element  E g arr 0  name will give you  k1   arr 1  value will give you  hi    Maybe you want to do something like   var obj        obj k1    abc   obj k2    hi   obj k3    oa    alert   obj k2     obj k2

User · Answer

Find one element  To find the element with a given name in an array you can use find   arr find item  gt item name   k1      Note that find will return just one item  namely the first match         name    k1      value    abc      Find all elements  In your original array there s only one item occurrence of each name    If the array contains multiple elements with the same name and you want them all then use filter  which will return an array    x000D   x000D  var arr       x000D  arr push  name  k1   value  abc     x000D  arr push  name  k2   value  hi     x000D  arr push  name  k3   value  oa     x000D  arr push  name  k1   value  def     x000D   x000D  var item  x000D   x000D     find the first occurrence of item with name  k1  x000D  item   arr find item  gt item name   k1    x000D  console log item   x000D   x000D     find all occurrences of item with name  k1  x000D     now item is an array x000D  item   arr filter item  gt item name   k1    x000D  console log item   x000D   x000D   x000D    Find indices  Similarly  for indices you can use findIndex  for finding the first match  and filter   map to find all indices    x000D   x000D  var arr       x000D  arr push  name  k1   value  abc     x000D  arr push  name  k2   value  hi     x000D  arr push  name  k3   value  oa     x000D  arr push  name  k1   value  def     x000D   x000D  var idx  x000D   x000D     find index of the first occurrence of item with name  k1  x000D  idx   arr findIndex item  gt item name     k1    x000D  console log idx  arr idx  value   x000D   x000D     find indices of all occurrences of item with name  k1  x000D     now idx is an array x000D  idx   arr map  item  i    gt  item name     k1    i       filter String   x000D  console log idx   x000D   x000D   x000D

User · Answer

I know this question is old  but no one has mentioned a native solution yet   If you re not trying to support archaic browsers  which you shouldn t be at this point   you can use array filter    x000D   x000D  var arr       x000D  arr push  name  k1   value  abc     x000D  arr push  name  k2   value  hi     x000D  arr push  name  k3   value  oa     x000D   x000D  var found   arr filter function item    return item name      k1       x000D   x000D  console log  found   found 0    x000D  Check the console  x000D   x000D   x000D    You can see a list of supported browsers here   In the future with ES6  you ll be able to use array find

User · Answer

You can t do what you re asking natively with an array  but javascript objects are hashes  so you can say     var hash       hash  k1      abc         Then you can retrieve using bracket or dot notation   alert hash  k1        alerts  abc  alert hash k1      also alerts  abc    For arrays  check the underscore js library in general and the detect method in particular   Using detect you could do something like       detect arr  function x    return x name     k1        Or more generally  MyCollection   function       this arr          MyCollection prototype getByName   function name      return   detect this arr  function x    return x name    name        MyCollection prototype push   function item      this arr push item      etc

[javascript] get one item from an array of name,value JSON

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