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JavaScript Comparison Operators

Comparison operators are used to compare two values and return a Boolean value (true or false) indicating whether the comparison is true or false.

The following are the comparison operators in JavaScript:

  • ==: Equal to - returns true if the two values are equal.

  • ===: Strictly equal to - returns true if the two values are equal and have the same data type.

  • !=: Not equal to - returns true if the two values are not equal.

  • !==: Strictly not equal to - returns true if the two values are not equal or have different data types.

  • <: Less than - returns true if the first value is less than the second value.

  • >: Greater than - returns true if the first value is greater than the second value.

  • <=: Less than or equal to - returns true if the first value is less than or equal to the second value.

  • >=: Greater than or equal to - returns true if the first value is greater than or equal to the second value.

Below are some examples of how to use comparison operators in JavaScript:

let a = 5;
let b = 10;

console.log(a == b); // false
console.log(a != b); // true
console.log(a < b); // true
console.log(a > b); // false
console.log(a <= b); // true
console.log(a >= b); // false

In the example above:

  • We compare the values of a and b using different comparison operators. For example, a < b is true because 5 is less than 10.
note

When using the == operator, JavaScript performs type coercion to try to compare the two values. For example, 5 == '5' is true because JavaScript will convert the string '5' to the number 5 before making the comparison. However, it's generally better to use the === operator when comparing values to avoid unexpected results due to type coercion.

Logical Operators​

In JavaScript, logical operators are used to combine two or more Boolean expressions and return a Boolean value. The following are the three logical operators in JavaScript:

  • &&: Logical AND - returns true if both expressions are true.

  • ||: Logical OR - returns true if at least one expression is true.

  • !: Logical NOT - returns the opposite of the expression's Boolean value.

Below are some examples of how to use logical operators in JavaScript:

let a = 5;
let b = 10;
let c = 15;

console.log(a < b && b < c); // true
console.log(a < b || b > c); // true
console.log(!(a < b)); // false

In the example above:

  • We use the logical operators &&, ||, and ! to combine multiple Boolean expressions. For example, a < b && b < c is true because both expressions are true (5 is less than 10 and 10 is less than 15).

Logical operators have short-circuit evaluation, implying that the second expression is not evaluated if the first expression alone can determine the result.

This means that true || any_expression always returns true, regardless of the value of any_expression, and thus any_expression is not evaluated.