Object.is()

Why Object.is ?

Object.is () checks whether the two values ​​are of the same value. The two values ​​are the same when one of the following is true:

• when they both have the same object
• both when and when
• when both are +0
• when both are -0
• both right and wrong
• two characters of the same length, when they are the same character in the same order
• when they are both NaN
• when both are undefined
• when both are empty
• or both are non-zero and not both NaN and both have the same value.
• This is not the same as the == operator. == The operator applies the same difficulty to both sides before testing the equation (if not the same type) (but “==”), but Object.is does not force both values.

This is not the same as being equal to === operator. The operator === (and == operator) accepts -0 and +0 are equal and treats Number.NaN as not equal to NaN.

Syntax:

Object.is(arr1, arr2);

• arr1: The first value to compare.
• arr2: The second value to compare.

---

arr1	arr2	==	===	Object.is
undefined	undefined	true	true	true
null	null	true	true	true
true	true	true	true	true
false	false	true	true	true
“foo”	“foo”	true	true	true
{ foo: “bar” }	x	true	true	true
0	0	true	true	true
+0	-0	true	true	false
0	false	true	false	false
“”	0	true	false	false
“0”	0	true	false	false
“17”	17	true	false	false
[1,2]	“1,2”	true	false	false
new String(“foo”)	“foo”	true	false	false
null	undefined	true	false	false
null	false	false	false	false
undefined	false	false	false	false
new String(“foo”)	new String(“foo”)	false	false	false
0	null	false	false	false
0	NaN	false	false	false
“foo”	NaN	false	false	false
NaN	NaN	false	false	true
{ foo: “bar” }	{ foo: “bar” }	false	false	false

---

JavaScript Object.is Example

        var test = { a: 1 };
        console.log( Object.is(test, test) )

        console.log( Object.is(null, null) )
        console.log( Object.is(0, -0) )
        console.log( Object.is(-0, -0) )
        console.log(Object.is(NaN, 0 / 0))

        Object.is('foo', 'foo');
        console.log(Object.is(window, window));

        Object.is('foo', 'bar');
        console.log(Object.is([], []));

output:

true
true
false
true
true
true
false

---

Polyfill

if (!Object.is) {
  Object.is = function(x, y) {
    // SameValue algorithm
    if (x === y) { // Steps 1-5, 7-10
      // Steps 6.b-6.e: +0 != -0
      return x !== 0 || 1 / x === 1 / y;
    } else {
      // Step 6.a: NaN == NaN
      return x !== x && y !== y;
    }
  };
}

---

Browser Support

Chrome	30
Edge	yes
Firefox	22
Internet Explorer	no
Opera	yes
Safari	9
Android webview	yes
Chrome for Android	yes
Edge mobile	yes
Firefox for Android	22
Opera Android	yes