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while loop – JavaScript

Summary

To create a while loop in JavaScript, use the while keyword:

let i = 0;

while (i < 10) {
  // Insert code here
  i++;
}

Details

A while loop lets you easily repeat a block of code multiple times.

To write a while loop, first declare your counter variable. Unlike a for loop, you declare your counter outside of the loop.

let i = 0;

Next, write the skeleton of the while loop.

let i = 0;

while () {

}

Next, write the condition to test against in parentheses.

let i = 0;

while (i < 10) {

}

Next, add an increment or decrement statement to the end of your loop. Without this, you might accidentally create an infinite loop!

let i = 0;

while (i < 10) {

  i++;
}

Lastly, add the code you want to repeat.

let i = 0;

while (i < 10) {
  console.log("Hello world");
  i++;
}

Demo

Exercises

Try the following statements in the console:

let i = 0;

while (i < 5) {
  console.log("Hello world");
  i++;
}

You should see ‘hello world’ print out 5 times, or the phrase ‘hello world’ with a number 5 next to it.

References

while statement on MDN

Back to: JavaScript Reference > JS Loops