JavaScript Code

For Loop

In JavaScript, For loop statement is used to execute a block of code repeatedly based on a condition.

Syntax

The syntax of For loop statement in JavaScript is

for (initialisation; condition; update) {
  //code
}

where

• for is keyword.
• initialisation is where variables are initialised.
• condition is a boolean expression.
• update is where variables are updated.
• code is any valid JavaScript code.

For loop execution starts with initialisation, then condition evaluation. If condition is true, then code inside for loop is executed, then update happens. After update, condition is evaluated, if true, code is execute, and so on. If condition is false, then for loop execution is completed.

Examples

1. In the following program, we use For loop to print 'hello world' 5 times.

for (i = 0; i < 5; i++) {
    console.log('hello world');
}

2. In the following program, we use For loop to find factorial of a number.

n = 5;
factorial = 1;
for (i = 2; i <= n; i++) {
    factorial *= i;
}
console.log(n+'! = '+ factorial);