How do I convert array of Objects into one Object in JavaScript

Question

I have an array of objects         key    11   value    1100     hashKey    00X         key    22   value    2200     hashKey    018        How do I convert it into the following by JavaScript       quot 11 quot    quot 1100 quot      quot 22 quot    quot 2200 quot

User · Answer

I like the functional approach to achieve this task:

var arr = [{ key:"11", value:"1100" }, { key:"22", value:"2200" }];
var result = arr.reduce(function(obj,item){
  obj[item.key] = item.value; 
  return obj;
}, {});

Note: Last {} is the initial obj value for reduce function, if you won't provide the initial value the first arr element will be used (which is probably undesirable).

https://jsfiddle.net/GreQ/2xa078da/

User · Answer

You re probably looking for something like this    x000D   x000D     original x000D  var arr      x000D     key    11   value    1100     hashKey    00X     x000D     key    22   value    2200     hashKey    018    x000D     x000D   x000D    convert x000D  var result       x000D  for  var i   0  i  lt  arr length  i      x000D    result arr i  key    arr i  value  x000D    x000D   x000D  console log result   x000D   x000D   x000D

User · Answer

Use lodash   const obj     keyBy arrayOfObjects   keyName

User · Answer

You can use the mapKeys lodash function for that  Just one line of code    Please refer to this complete code sample  copy paste this into repl it or similar    import   from  lodash      or commonjs     const     require  lodash     let a      id  23  title   meat       id  45  title   fish       id  71  title   fruit     let b     mapKeys a   id    console log b      b        23     id  23  title   meat           45     id  45  title   fish           71     id  71  title   fruit

User · Answer

Trying to fix this answer in How do I convert array of Objects into one Object in JavaScript    this should do it    x000D   x000D  var array     x000D       key  k1  value  v1    x000D       key  k2  value  v2    x000D       key  k3  value  v3   x000D     x000D  var mapped   array  map item   gt      item key   item value       x000D  var newObj   Object assign        mapped    x000D  console log newObj    x000D   x000D   x000D     One-liner   var newObj   Object assign         array map item   gt      item key   item value

User · Answer

Tiny ES6 solution can look like   x000D   x000D  var arr     key  11   value  1100    key  22   value  2200     var object   arr reduce     obj  item    gt  Object assign obj     item key   item value           console log object  x000D   x000D   x000D   Also  if you use object spread  than it can look like  var object   arr reduce  obj  item    gt       obj   item key   item value          One more solution that is 99  faster is tested on jsperf   var object   arr reduce  obj  item    gt   obj item key    item value  obj         Here we benefit from comma operator  it evaluates all expression before comma and returns a last one after last comma   So we don t copy obj each time  rather assigning new property to it

User · Answer

Based on answers suggested by many authors  I created a JsPref test scenario  https   jsperf com array2object82364  Below are the screenshots of performance  It is a little shocking to me to see  chrome result is in contrast to firefox and edge  even after running it several times

User · Answer

Update  The world kept turning  Use a functional approach instead   Here you go   var arr      key   11   value   1100       key   22   value   2200      var result       for  var i 0  len arr length  i  lt  len  i          result arr i  key    arr i  value    console log result       11   1000   22   2200

User · Answer

Here s how to dynamically accept the above as a string and interpolate it into an object   var stringObject     Object   key  11   value  1100     hashKey  00X    Object   key  22   value  2200     hashKey  018       function interpolateStringObject stringObject      var jsObj         var processedObj   stringObject split   Object         processedObj   processedObj 1  split            each processedObj  function  i  v          jsObj v split  key    1  split      0     v split  value    1  split      0  replace     g               return jsObj    var t   interpolateStringObject stringObject     t is the object you want   http   jsfiddle net 3QKmX 1

User · Answer

Using Object fromEntries    x000D   x000D  const array     x000D        key   key1   value   value1     x000D        key   key2   value   value2     x000D     x000D   x000D  const obj   Object fromEntries array map item   gt   item key  item value     x000D   x000D  console log obj   x000D   x000D   x000D

User · Answer

A clean way to do this using modern JavaScript is as follows   const array         name   something   value   something         name   somethingElse   value   something else         const newObject   Object assign        array map item   gt      item name   item value            gt  gt    something   something   somethingElse   something else

User · Answer

x000D   x000D     original x000D  var arr      x000D      key   11   x000D      value   1100   x000D        hashKey   00X  x000D       x000D      x000D      key   22   x000D      value   2200   x000D        hashKey   018  x000D      x000D     x000D   x000D     My solution x000D  var obj       x000D  for  let i   0  i  lt  arr length  i      x000D    obj arr i  key    arr i  value  x000D    x000D  console log obj  x000D   x000D   x000D

User · Answer

Using Underscore js   var myArray       Object   key  11   value  1100     hashKey  00X      Object   key  22   value  2200     hashKey  018      var myObj     object   pluck myArray   key      pluck myArray   value

[javascript] How do I convert array of Objects into one Object in JavaScript?

Examples related to javascript