What is = in JavaScript?
Equal to (=) is an assignment operator, which sets the variable on the left of the = to the value of the expression that is on its right. This operator assigns lvalue to rvalue.
For example, Writing a=10 is fine. If we write 10=10, 'a' = 10 or 'a' = 'a', it will result in a reference error.
In this tutorial, you will learn:
What is == in JavaScript?
Double equals (==) is a comparison operator, which transforms the operands having the same type before comparison.
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.
What is === 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 2 with "2" using ===, then it will return a false value.
Why use = in JavaScript?
Here are the important uses of = in JavaScript:
= JavaScript operator assigns a value to the left operand depends on the value of operand available on the right side. The first operand should be a variable.
The basic assignment operator is =, that assigns the value of one operand to another. That is, a = b assigns the value of b to a.
Why use == in JavaScript?
Here are the important uses of == in JavaScript:
The == operator is an equality operator. It checks whether its two operands are the same or not by changing expression from one data type to others. You can use == operator in order to compare the identity of two operands even though, they are not of a similar type.
How === Works Exactly?
- Strict equality === checks that two values are the same or not.
- Value are not implicitly converted to some other value before comparison.
- If the variable values are of different types, then the values are considered as unequal.
- If the variable are of the same type, are not numeric, and have the same value, they are considered as equal.
- Lastly, If both variable values are numbers, they are considered equal if both are not NaN (Not a Number) and are the same value.
Example of =
In the below program, there are two variables "a" and "b". We are adding and printing their values using a third variable, "c". The sum of the value of variable "a" and "b" is 7. Therefore, the output is 7.
<!DOCTYPE html>
<html>
<body>
<h2>JavaScript Operators</h2>
<p>a = 2, b = 5, calculate c = a + b, and display c:</p>
<p id="demonstration"></p>
<script>
var a = 2;
var b = 5;
var c= a + b;
document.getElementById("demonstration").innerHTML = c;
</script>
</body>
</html>
Output:
a = 2, b = 5, calculate c = a + b, and display c:
7
Example of ==
In the below program, we have declared one variable "a" having value 10. Lastly, the statement a == 20 returns false as the value of a is 10.
<!DOCTYPE html>
<html>
<body>
<p id="demonstration"></p>
<script>
var a = 10;
document.getElementById("demonstration").innerHTML = (a == 20);
</script>
</body>
</html>
Output:
false
Example of ===
In the below program, the value of variable x is 10. It is compared to 10 written in double-quotes, which is considered as a string, and therefore, the values are not strictly the same. The output of the program is false.
<!DOCTYPE html>
<html>
<body>
<p id="demo"></p>
<script>
var x = 10;
document.getElementById("demo").innerHTML = (x === "10");
</script>
</body>
</html>
Output:
false
= Vs == VS === in JavaScript
Here are the important differences between =, ==, and ===
| = | == | === |
|---|
| = in JavaScript is used for assigning values to a variable. | == in JavaScript is used for comparing two variables, but it ignores the datatype of variable. | === is used for comparing two variables, but this operator also checks datatype and compares two values. |
| It is called as assignment operator | It is called as comparison operator | It is also called as comparison operator |
| The assignment operator can evaluate to the assigned value | Checks the equality of two operands without considering their type. | Compares equality of two operands with their types. |
| It does not return true or false | Return true if the two operands are equal. It will return false if the two operands are not equal. | It returns true only if both values and data types are the same for the two variables. |
| = simply assign one value of variable to another one. | == make type correction based upon values of variables. | === takes type of variable in consideration. |
| == will not compare the value of variables at all. | The == checks for equality only after doing necessary conversations. | If two variable values are not similar, then === will not perform any conversion. |
KEY DIFFERENCES:
- = is used for assigning values to a variable, == is used for comparing two variables, but it ignores the datatype of variable whereas === is used for comparing two variables, but this operator also checks datatype and compares two values.
- = is called as assignment operator, == is called as comparison operator whereas It is also called as comparison operator.
- = does not return true or false, == Return true only if the two operands are equal while === returns true only if both values and data types are the same for the two variables.
