Introduction :
In this tutorial will learn Difference Between =, ==, and === in JavaScript with Examples. In Javascript, we have couple of options for checking equality. we’ll explore here similarities and difference between = (single equal) and ==(double equals) and === (triple equals) in JavaScript
- = (Single equal): Known as assignment operator it always assign value to variable.
- == (Double equals): Known as the equality or abstract comparison operator
- === (Triple equals): Known as the identity or strict comparison operator
What is =(equal to) in JavaScript?
Equal to (=) is an assignment operator, which sets the variable value on the left of the = to the value of the expression that is on its right.
For example, if we have variable var A and want to assign value 10 to var A then will write below syntax:
var A= 10;
What is == (double equal to) in JavaScript?
Double equals operator (==) is known as comparison operator or equality operator or abstract comparison operator.
So, when you compare string with a number, JavaScript converts any string to a number. An empty string is always converts to zero. A string with no numeric value is converts to NaN (Not a Number), which returns false.
==(double Equals operator) only compare value of two variable. it only checks for equality of two variable value without checking data type.
What is === (triple equals) in JavaScript?
=== (Triple equals) is a strict equality comparison operator in JavaScript, which returns false for the values which are not of a similar type. This operator performs type casting for equality. If we compare 10 with “10” using ===, then it will return a false value.
The Difference between == Double equals Operator) and === (Triple equals Operator):
- == converts the variable values to the same type before performing comparison. This is called type conversion.
- == converts the variable values to the same type before performing comparison. This is called type conversion.
Let’s take an example:
var A = 1;
var AB = 1;
var A_string = “1”; // note: this is string data type
console.log(A == AB); // true
console.log(A === AB); // true
console.log(A == A_string); // true
console.log(A === A_string); // false
line 4 : console.log(A == AB) returns true because both variable values are same.
line 5 : console.log(A === AB) returns true because both variable values and data type are same.
line 6 : console.log(A == A_string) returns true because both variable values are same without type checking.
line 7: console.log(A === A_string) returns false because both variable values are same but datatype are different.
KEY DIFFERENCES:
| == (Double Equals Operator) | === (Triple Equals Operator) |
| it is used for comparing two variables, but it ignores the datatype of variable. | it is used for comparing two variables, but this operator also checks datatype and compares two values. |
| it is comparison operator | it is also comparison oprator |
| it checks equality of to variable without checking data type | it checks quality of two variable with considering the datatype |
| ==make type correction based upon values of variables. | === takes type of variable in consideration. |
| == checks for equality only after doing necessary conversations. | two variable values are not similar, then === will not perform any conversion. |
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