Loops (for, while, do...while)

JavaScript offers several looping structures to help execute code repeatedly based on certain conditions.

1. for Loop

The for loop is one of the most commonly used loops. It's ideal when you know how many times you need to execute a block of code. It has three parts: initialization, condition, and increment/decrement.

for (let i = 0; i < 5; i++) {
  console.log(i);
}

Explanation:

Initialization (let i = 0): Sets the starting point.
Condition (i < 5): Loop runs as long as this is true.
Increment/Decrement (i++): Updates the variable after each loop.
Example Use Case: Looping through an array

const fruits = ["apple", "banana", "cherry"];
for (let i = 0; i < fruits.length; i++) {
  console.log(fruits[i]);
}

2. while Loop

The while loop executes as long as the condition is true. This loop is helpful when you don't know the exact number of iterations in advance.

let count = 0;
while (count < 5) {
  console.log(count);
  count++;
}

Explanation:

The condition (count < 5) is evaluated before each loop.
If true, the code block runs.
Once the condition is false, the loop stops.

Example Use Case: User input validation

let password;
while (password !== "secret") {
  password = prompt("Enter the correct password:");
}
console.log("Access granted");

3. do...while Loop

The do...while loop is similar to the while loop but guarantees that the code block runs at least once, as the condition is checked after the loop body.

let num = 0;
do {
  console.log(num);
  num++;
} while (num < 5);

Explanation:

Runs the code in the do block once, then checks the while condition.
If the condition is true, it loops; if false, it exits.

Example Use Case: Executing a block once before a condition check

let answer;
do {
  answer = prompt("Type 'yes' to continue:");
} while (answer !== "yes");
console.log("Continuing...");

Summary

for loop: Use when you know the number of iterations.
while loop: Use when the number of iterations is unknown, but a condition is involved.
do...while loop: Use when you need the code to run at least once before condition checking.

Conditional statements in javascript (if, else if, else, switch)

Breaking and continuing loops