83

Is it possible to do a "deep" comparison of two object in Angular? What I would like to do is compare each key/value pair. For example:

Object 1

{
   key1: "value1",
   key2: "value2",
   key3: "value3"
}

Object 2

{
   key1: "value1",
   key2: "newvalue",
   key3: "value3" 
}

What I need is for the comparison to fail since only one of the key/value pairs is diffent. In other words ALL of the key/value pairs must match exactly or else failure. Is this something already built into Angular. I'm sure I could write my own service if I really needed to, but I was hoping it was already built in. Similar to angular.equals.

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4 Answers 4

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208

To compare two objects you can use:

angular.equals(obj1, obj2)

It does a deep comparison and does not depend on the order of the keys See AngularJS DOCS and a little Demo

var obj1 = {
  key1: "value1",
  key2: "value2",
  key3: {a: "aa", b: "bb"}
}

var obj2 = {
  key2: "value2",
  key1: "value1",
  key3: {a: "aa", b: "bb"}
}

angular.equals(obj1, obj2) //<--- would return true
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8 Comments

Note that angular.equals tests identity, not equality. TL;DR: angular.equals( { id: "12" }, { id: 12 } ) // is false
@bobjones angular.equals returns true based on identity OR deep equality, so your proposed example would return true. see the angular.equals documentation , specifically Two objects or values are considered equivalent if at least one of the following is true
@tommyTheHitMan: bobjones example returns false because, based on identity, "12"===12 // is false. Just try it out.
And if you need a diff object for tracking history for rollbacks, see this... gist.github.com/katowulf/6193808
A quick note: angular.equals() ignores all properties beginning with $, and all properties whose values are functions, when both arguments are objects.
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27

Assuming that the order is the same in both objects, just stringify them both and compare!

JSON.stringify(obj1) == JSON.stringify(obj2);
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5 Comments

angular.equals(obj1,obj2) should also work. It does not depend from the keys order and it is deep (it is called recursively) code.angularjs.org/1.2.0/docs/api/angular.equals
That would be a very bad assumption!
angular.toJson would also remove the $$hashKeys
This does not work if the order of properties is different. So JSON.stringify({a:1, b:1}) === JSON.stringify({b:1, a:1}) is false.
@PeterB feels like I mentioned that somewhere in the answer...
5

Bit late on this thread. angular.equals does deep check, however does anyone know that why its behave differently if one of the member contain "$" in prefix ?

You can try this Demo with following input

var obj3 = {}
obj3.a=  "b";
obj3.b={};
obj3.b.$c =true;

var obj4 = {}
obj4.a=  "b";
obj4.b={};
obj4.b.$c =true;

angular.equals(obj3,obj4);
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1 Comment

From the Angular documentation: "During a property comparison, properties of function type and properties with names that begin with $ are ignored." docs.angularjs.org/api/ng/function/angular.equals
2

I know it's kinda late answer but I just lost about half an hour debugging cause of this, It might save someone some time.

BE MINDFUL, If you use angular.equals() on objects that have property obj.$something (property name starts with $) those properties will get ignored in comparison.

Example:

var obj1 = {
  $key0: "A",
  key1: "value1",
  key2: "value2",
  key3: {a: "aa", b: "bb"}
}

var obj2 = {
  $key0: "B"
  key2: "value2",
  key1: "value1",
  key3: {a: "aa", b: "bb"}
}

angular.equals(obj1, obj2) //<--- would return TRUE (despite it's not true)
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