Javascript | Loops (for, while, do-while)

Loops are an essential part of programming and are used to repeat a block of code until a certain condition is met. In JavaScript, there are various types of loops that can be used for different purposes. In this article, we will cover the three basic loop types (for, while, and do-while), as well as the forEach method and the latest looping method introduced in ES6 (for…of).

For Loop: The for loop is used to repeat a block of code a fixed number of times. It consists of an initialization expression, a condition expression, and an increment expression. The syntax for a for loop is as follows:

for (initialization; condition; increment) {
  // code block to be executed
}

For example, the following loop prints the numbers from 1 to 10:

for (var i = 1; i <= 10; i++) {
  console.log(i);
}

While Loop: The while loop is used to repeat a block of code as long as a certain condition is true. It consists of a condition expression, and the code block to be executed. The syntax for a while loop is as follows:

while (condition) {
  // code block to be executed
}

For example, the following while loop prints the numbers from 1 to 10:

var i = 1;
while (i <= 10) {
  console.log(i);
  i++;
}

Do-While Loop: The do-while loop is similar to the while loop, but the condition is checked at the end of the loop instead of at the beginning. This means that the code block will be executed at least once, even if the condition is false. The syntax for a do-while loop is as follows:

do {
  // code block to be executed
} while (condition);

For example, the following do-while loop prints the numbers from 1 to 10:

var i = 1;
do {
  console.log(i);
  i++;
} while (i <= 10);

ForEach Method: The forEach method is used to loop through arrays in JavaScript. It is a more concise and readable way of iterating through arrays compared to traditional for loops. The syntax for a forEach loop is as follows:

array.forEach(function(item, index, array) {
  // code block to be executed
});

For example, the following forEach loop prints the elements of an array:

var arr = ["apple", "banana", "orange"];
arr.forEach(function(item, index) {
  console.log(index + ": " + item);
});

For…Of Loop: The for…of the loop is the latest looping method introduced in ES6. It is used to iterate through iterable objects, such as arrays and strings. It is a simpler and more readable way of looping compared to traditional for loops. The syntax for a for…of the loop is as follows:

for (let item of iterable) {
  // code block to be executed
}

For example, the following for…of loop prints the elements of an array:

var arr = ["apple", "banana", "orange"];
for (let item of arr) {
  console.log(item);
}

In conclusion, loops are an essential part of programming in JavaScript, and there are various types of loops that can be used for different purposes. The forEach method and the for…of loop are the latest and most convenient ways of looping in JavaScript introduced in ES6. By understanding the different types of loops and their usage, you can write more efficient and effective code.