JavaScript equality operator is used to check whether its two operands are equal, returning a Boolean result.
x == yThe === and == operators evaluate whether one value is equal to another == will also check if the values are equal after one of the values is converted into another type.
Note: The strict equality operator attempts to convert and compare operands that are of different types.
JavaScript equality operator
Simple example code.
<!DOCTYPE html>
<html>
<body>
<script>
console.log(1 == 1);
console.log('hello' == 'hello');
console.log('1' == 1);
console.log(0 == true);
</script>
</body>
</html>Output:
Other examples
console.log("string" === "string"); // -> true
console.log(1 === 1); // -> true
console.log(1 === "1"); // -> false
console.log(1 == "1"); // -> true
console.log("String" === "string"); // -> false
console.log("String" == "string"); // -> falseComparison with no type conversion
1 == 1; // true
"hello" == "hello"; // trueComparison with type conversion
"1" == 1; // true
1 == "1"; // true
0 == false; // true
0 == null; // false
0 == undefined; // false
0 == !!null; // true, look at Logical NOT operator
0 == !!undefined; // true, look at Logical NOT operator
null == undefined; // true
const number1 = new Number(3);
const number2 = new Number(3);
number1 == 3; // true
number1 == number2; // false
Comparison of objects
const object1 = {"key": "value"}
const object2 = {"key": "value"};
object1 == object2 // false
object2 == object2 // trueWhich equals operator (== vs ===) should be used in JavaScript comparisons?
Answer: Using the == operator (Equality)
true == 1; //true, because 'true' is converted to 1 and then compared
"2" == 2; //true, because "2" is converted to 2 and then compared
Using the === operator (Identity)
true === 1; //false
"2" === 2; //false
This is because the equality operator == does type coercion, meaning that the interpreter implicitly tries to convert the values before comparing.
On the other hand, the identity operator === does not do type coercion, and thus does not convert the values when comparing.
Do comment if you have any doubts or suggestions on this JS operator topic.
Note: The All JS Examples codes are tested on the Firefox browser and the Chrome browser.
OS: Windows 10
Code: HTML 5 Version