js-comparison.md

Comparison in JavaScript

Comparison operators are used to compare two values. They always return a boolean value.

Summary

Operator	Description	Example
==	Equals	if (x == y) { ... }
!=	Not equals	if (x != y) { ... }
===	Identical	if (x === y) { ... }
!==	Not identical	if (x !== y) { ... }
<	Less than	if (x < y) { ... }
<=	Less than or equal to	if (x <= y) { ... }
>	Greater than	if (x > y) { ... }
>=	Greater than or equal to	if (x >= y) { ... }
&&	And	if (x && y) { ... }
||	Or	if (x || y) { ... }
!	Not	if (!x) { ... }

Comparison Operators

== (EQUALS)

Use == to check if two values are equal.

if (<value1> == <value2>) {
    // block of code to be executed if the values are equal
}

<value1> and <value2> can be numbers, strings, arrays, objects, etc.

Example:

let x = 5;
let y = "5";

if (x == y) {
    console.log("x is equal to y"); // Output: "x is equal to y"
} else {
    console.log("x is not equal to y"); // Output: "x is not equal to y"
}

!= (NOT EQUALS)

Use != to check if two values are not equal.

if (<value1> != <value2>) {
    // block of code to be executed if the values are not equal
}

<value1> and <value2> can be numbers, strings, arrays, objects, etc.

Example:

let x = 5;
let y = "5";

if (x != y) {
    console.log("x is not equal to y"); // Output: "x is not equal to y"
} else {
    console.log("x is equal to y"); // Output: "x is equal to y"
}

=== (IDENTICAL)

Use === to check if two values are identical (equal and of the same type).

if (<value1> === <value2>) {
    // block of code to be executed if the values are identical
}

<value1> and <value2> can be numbers, strings, arrays, objects, etc.

Example:

let x = 5;
let y = "5";

if (x === y) {
    console.log("x is identical to y"); // Output: "x is identical to y"
} else {
    console.log("x is not identical to y"); // Output: "x is not identical to y"
}

!== (NOT IDENTICAL)

Use !== to check if two values are not identical (not equal and of the same type).

if (<value1> !== <value2>) {
    // block of code to be executed if the values are not identical
}

<value1> and <value2> can be numbers, strings, arrays, objects, etc.

Example:

let x = 5;
let y = "5";

if (x !== y) {
    console.log("x is not identical to y"); // Output: "x is not identical to y"
} else {
    console.log("x is identical to y"); // Output: "x is identical to y"
}

> (GREATER THAN)

Use > to check if a value is greater than another value.

if (<value1> > <value2>) {
    // block of code to be executed if the value1 is greater than value2
}

<value1> and <value2> can be numbers, strings, arrays, objects, etc.

Example:

let x = 5;
let y = 10;

if (x > y) {
    console.log("x is greater than y"); // Output: "x is greater than y"
} else {
    console.log("x is not greater than y"); // Output: "x is not greater than y"
}

< (LESS THAN)

Use < to check if a value is less than another value.

if (<value1> < <value2>) {
    // block of code to be executed if the value1 is less than value2
}

<value1> and <value2> can be numbers, strings, arrays, objects, etc.

Example:

let x = 5;
let y = 10;

if (x < y) {
    console.log("x is less than y"); // Output: "x is less than y"
} else {
    console.log("x is not less than y"); // Output: "x is not less than y"
}

>= (GREATER THAN OR EQUAL TO)

Use >= to check if a value is greater than or equal to another value.

if (<value1> >= <value2>) {
    // block of code to be executed if the value1 is greater than or equal to value2
}

<value1> and <value2> can be numbers, strings, arrays, objects, etc.

Example:

let x = 5;
let y = 10;

if (x >= y) {
    console.log("x is greater than or equal to y"); // Output: "x is greater than or equal to y"
} else {
    console.log("x is not greater than or equal to y"); // Output: "x is not greater than or equal to y"
}

<= (LESS THAN OR EQUAL TO)

Use <= to check if a value is less than or equal to another value.

if (<value1> <= <value2>) {
    // block of code to be executed if the value1 is less than or equal to value2
}

<value1> and <value2> can be numbers, strings, arrays, objects, etc.

Example:

let x = 5;
let y = 10;

if (x <= y) {
    console.log("x is less than or equal to y"); // Output: "x is less than or equal to y"
} else {
    console.log("x is not less than or equal to y"); // Output: "x is not less than or equal to y"
}

Logical Operators

&& (AND)

Use && to execute a block of code if both conditions are true.

if (<condition1> && <condition2>) {
    // block of code to be executed if the condition1 and condition2 are true
}

<condition1> and <condition2> are conditions. They return a boolean value.

Example:

for (let i = 0; i < 10; i++) {
    if (i > 5 && i < 8) {
        console.log(i); // Output: 6, 7
    }
}

|| (OR)

Use || to execute a block of code if either condition is true.

if (<condition1> || <condition2>) {
    // block of code to be executed if the condition1 or condition2 is true
}

<condition1> and <condition2> are conditions. They return a boolean value.

Example:

for (let i = 0; i < 10; i++) {
    if (i > 5 || i < 8) {
        console.log(i); // Output: 0, 1, 2, 3, 4, 5, 8, 9
    }
}

! (NOT)

Use ! to execute a block of code if the condition is false.

if (!<condition>) {
    // block of code to be executed if the condition is false
}

<condition> is a condition. It returns the opposite of a boolean value.

Example:

for (let i = 0; i < 10; i++) {
    if (!(i > 5)) {
        console.log(i); // Output: 0, 1, 2, 3, 4
    }
}

Results of logical comparisons

AND (&&)

value1	value2	result
true	true	true
true	false	false
false	true	false
false	false	false

OR (||)

value1	value2	result
true	true	true
true	false	true
false	true	true
false	false	false

NOT (!)

value	result
true	false
false	true