While Loop In JavaScript - JavaScript Tutorials

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While loop

JavaScript loops are used to repeatedly run a block of code - until a certain condition is met. JavaScript offers several options to repeatedly run a block of code like while, do while, for and for-in.

var hits = 1;
var number = 1;
while (number <= 50) 
{
        hits += hits;
	number++;
}
alert("Hits = " + hits);  // => Hits = 1275

The condition is first evaluated. If true, the block of statements following the while statement is executed. This is repeated until the condition becomes false. This is known as a pre-test loop because the condition is evaluated before the block is executed.

The number++ statement is called the updater. Removing it will result in an infinite loop. You must always include a statement in a loop that guarantees the termination of the loop or else you'll run into this problem.