Loops
Loops are used to execute a block of statements multiple times. The number of times the loop has to run can depend on a condition, or the number of elements in the given collection.
JavaScript supports following loop statements .
- for loop is used to execute a block of code based on a condition.
- for…in loop is used to execute a block of code for each key in the key-value pairs of the given object.
- for…of loop is used to execute a block of code for each item in the given iterator.
- while loop is used to execute a block of code based on a condition.
- do-while loop is used to execute a block of code based on a condition, but the block of code runs at-least once.
We can break the loop or continue with the next iteration using following statements.
Examples
for loop
const fruits = ["apple", "banana", "cherry"];
for ( let index = 0; index < fruits.length; index++ ) {
console.log(fruits[index]);
}
for…in loop
const fruits = ["apple", "banana", "cherry"];
for (let index in fruits) {
console.log(fruits[index]);
}
for…of loop
const fruits = ["apple", "banana", "cherry"];
for (let item of fruits) {
console.log(item);
}
while loop
const fruits = ["apple", "banana", "cherry"];
let index = 0;
while ( index < fruits.length ) {
console.log(fruits[index]);
index++;
}
do-while loop
const fruits = ["apple", "banana", "cherry"];
let index = 0;
do {
console.log(fruits[index]);
index++;
} while ( index < fruits.length );
break
const fruits = ["apple", "banana", "cherry"];
for (let index in fruits) {
if (index == 1) {
break;
}
console.log(fruits[index]);
}
continue
const fruits = ["apple", "banana", "cherry"];
for (let index in fruits) {
if (index == 1) {
continue;
}
console.log(fruits[index]);
}