I have an object such as :

var inspectionMapping = {'a_pillar_lh' : "A Pillar LH",
                       'b_pillar_lh'  : "B Pillar LH"};

console.log(inspectionMapping['a_pillar_lh']);
// Which gives me correct "A Pillar LH".

I am able to get the value corresponding to key.

But I am not able to get the key corresponding to value in javascript Object.

Such as I have "A Pillar LH" and I need to get the corresponding key which is a_pillar_lh.

I have tried to use indexOf but no success.

I have an object such as :

var inspectionMapping = {'a_pillar_lh' : "A Pillar LH",
                       'b_pillar_lh'  : "B Pillar LH"};

console.log(inspectionMapping['a_pillar_lh']);
// Which gives me correct "A Pillar LH".

I am able to get the value corresponding to key.

But I am not able to get the key corresponding to value in javascript Object.

Such as I have "A Pillar LH" and I need to get the corresponding key which is a_pillar_lh.

I have tried to use indexOf but no success.

• javascript
• arrays
• node.js

• Something like Object.keys(obj) – Rayon Commented Apr 6, 2016 at 10:43
• You have to loop through the keys, checking if the value matches your search. – Poul Bak Commented Apr 6, 2016 at 10:44
• jsfiddle/rayon_1990/n0y75guq – Rayon Commented Apr 6, 2016 at 10:51
• @RayonDabre : Jsfiddle example works for me. Thanks buddy :) – RISHABH BANSAL Commented Apr 6, 2016 at 11:04

3 Answers 3

You can simply fetch all the keys using Object.keys() and then use .find() function to get the key out from that array, and then nicely wrap it in a function to make it modular.

var inspectionMapping = {
  'a_pillar_lh': "A Pillar LH",
  'b_pillar_lh': "B Pillar LH"
};

Object.prototype.getKey = function(value) {
  var object = this;
  return Object.keys(object).find(key => object[key] === value);
};


alert(inspectionMapping.getKey("A Pillar LH"));

EDIT For those who don't want to use ES6

Object.prototype.getKey = function(value) {
      var object = this;
      for(var key in object){
         if(object[key]==value) return key;
      }
};

Try this.

Object.keys(inspectionMapping).find(key => inspectionMapping[key] === 'A Pillar LH');

If anyone is interested in a Lodash solution to this, here's one I monly use. This method inverts the object, swapping keys for values, and then finds the key by looking up the value against this new object.

var inspectionMapping = {
	'a_pillar_lh': "A Pillar LH",
	'b_pillar_lh': "B Pillar LH"
};

var getKey = function( obj, value ) {
	var inverse = _.invert( obj );
	return _.get( inverse, value, false );
};

alert( 'The key for "A Pillar LH" is "' + getKey( inspectionMapping, 'A Pillar LH' ) + '"' );

<script src="https://cdnjs.cloudflare./ajax/libs/lodash.js/4.17.4/lodash.min.js"></script>