JavaScript Comparison and Logical Operators
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JavaScript Comparison Operators
Comparison operators compare two values and give back a boolean value: either true or false. Comparison operators are used in decision making and loops.
| Operator | Description | Example |
|---|---|---|
== |
Equal to: true if the operands are equal |
5==5; //true |
!= |
Not equal to: true if the operands are not equal |
5!=5; //false |
=== |
Strict equal to: true if the operands are equal and of the same type |
5==='5'; //false |
!== |
Strict not equal to: true if the operands are equal but of different type or not equal at all |
5!=='5'; //true |
> |
Greater than: true if the left operand is greater than the right operand |
3>2; //true |
>= |
Greater than or equal to: true if the left operand is greater than or equal to the right operand |
3>=3; //true |
< |
Less than: true if the left operand is less than the right operand |
3<2; //false |
<= |
Less than or equal to: true if the left operand is less than or equal to the right operand |
2<=2; //true |
Example 1: Equal to Operator
const a = 5, b = 2, c = 'hello';
// equal to operator
console.log(a == 5); // true
console.log(b == '2'); // true
console.log(c == 'Hello'); // false
== evaluates to true if the operands are equal.
Note: In JavaScript, == is a comparison operator, whereas = is an assignment operator. If you mistakenly use = instead of ==, you might get unwanted result.
Example 2: Not Equal to Operator
const a = 3, b = 'hello';
// not equal operator
console.log(a != 2); // true
console.log(b != 'Hello'); // true
!= evaluates to true if the operands are not equal.
Example 3: Strict Equal to Operator
const a = 2;
// strict equal operator
console.log(a === 2); // true
console.log(a === '2'); // false
=== evaluates totrue if the operands are equal and of the same type. Here 2 and ‘2’ are the same numbers but the data type is different. And === also checks for the data type while comparing.
Note: The difference between == and === is that:
== evaluates to true if the operands are equal, however, === evaluates to true only if the operands are equal and of the same type
Example 4: Strict Not Equal to Operator
const a = 2, b = 'hello';
// strict not equal operator
console.log(a !== 2); // false
console.log(a !== '2'); // true
console.log(b !== 'Hello'); // true
!== evaluates to true if the operands are strictly not equal. It’s the complete opposite of strictly equal ===.
In the above example, 2 !== '2' gives true. It’s because their types are different even though they have the same value.
Example 5: Greater than Operator
const a = 3;
// greater than operator
console.log(a > 2); // true
> evaluates to true if the left operand is greater than the right operand.
Example 6: Greater than or Equal to Operator
const a = 3;
// greater than or equal operator
console.log(a >= 3); //true
>= evaluates to true if the left operand is greater than or equal to the right operand.
Example 7: Less than Operator
const a = 3, b = 2;
// less than operator
console.log(a < 2); // false
console.log(b < 3); // true
< evaluates to true if the left operand is less than the right operand.
Example 8: Less than or Equal to Operator
const a = 2;
// less than or equal operator
console.log(a <= 3) // true
console.log(a <= 2); // true
<= evaluates to true if the left operand is less than or equal to the right operand.
JavaScript Logical Operators
Logical operators perform logical operations: AND, OR and NOT.
| Operator | Description | Example |
|---|---|---|
&& |
Logical AND: true if both the operands/boolean values are true, else evaluates to false |
true && false; // false |
|| |
Logical OR: true if either of the operands/boolean values is true. evaluates to false if both are false |
true || false; // true |
! |
Logical NOT: true if the operand is false and vice-versa. |
!true; // false |
Example 9: Logical AND Operator
const a = true, b = false;
const c = 4;
// logical AND
console.log(a && a); // true
console.log(a && b); // false
console.log((c > 2) && (c < 2)); // false
&& evaluates to true if both the operands are true, else evaluates to false.
Note: You can also use logical operators with numbers. In JavaScript, 0 is false and all non-zero values are true.
Example 10: Logical OR Operator
const a = true, b = false, c = 4;
// logical OR
console.log(a || b); // true
console.log(b || b); // false
console.log((c>2) || (c<2)); // true
|| evaluates to true if either of the operands is true. If both operands are false, the result is false.
Example 11: Logical NOT Operator
const a = true, b = false;
// logical NOT
console.log(!a); // false
console.log(!b); // true
! evaluates to true if the operand is false and vice-versa.
