JavaScript Loops
In JavaScript, loops are used to repeatedly execute a block of code until a certain condition is met. There are several types of loops in JavaScript:
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1. For Loop:
A for loop is used when you know beforehand how many times the loop should run.
for (initialization; condition; iteration) {
// code to be executed
}
Example: 👇
for (let i = 0; i < 5; i++) {console.log(i);
}
2. While Loop:
A while loop is used when the number of iterations is not known beforehand, and the loop runs as long as a specified condition is true.
while (condition) {
// code to be executed
}
Example:
let i = 0;
while (i < 5) {
console.log(i);
i++;
}
3. Do-While Loop:
Similar to the while loop, but the code block is executed at least once before the condition is tested.
do {
// code to be executed
} while (condition);
Example:
let i = 0;
do {
console.log(i);
i++;
} while (i < 5);
4. For...In Loop:
Iterates over the enumerable properties of an object.
for (variable in object) {
// code to be executed
}
Example:
const person = {
name: 'John',
age: 30,
gender: 'male'
};
for (let key in person) {
console.log(key + ': ' + person[key]);
}
5. For...Of Loop:
Introduced in ECMAScript 2015 (ES6), it iterates over iterable objects (arrays, strings, maps, sets, etc.).
for (variable of iterable) {
// code to be executed
}
Example:
const fruits = ['apple', 'banana', 'orange'];
for (let fruit of fruits) {
console.log(fruit);
}
When using loops, ensure that there's a way to exit the loop; otherwise, it will run infinitely, causing the browser or Node.js environment to become unresponsive. Always have a clear exit condition in your loops.
