JavaScript Loops

Loops can execute a block of code a number of times.

JavaScript Loops

Loops are handy, if you want to run the same code over and over again, each time with a different value.

Often this is the case when working with arrays:

Instead of writing:

Example Code

javascript

Try it Yourself

text += cars[0] + "**";
text += cars[1] + " ";

 text += cars[2] + " ";
text += cars[3] + " ";

 text += cars[4] + " ";
text += cars[5] + " ";

The For Loop

The for statement creates a loop with 3 optional expressions:

for (expr1; expr2; expr3) { // code block to be executed }

exp1 is executed one time before the execution of the code block.

exp2 defines the condition for executing the code block.

exp3 is executed every time the code block has been executed.

Example

Example Code

javascript

Try it Yourself

for (let i = 0; i   If you forget to increase the variable used in the condition, the loop will never end.
> This will crash your browser.

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## The Do While Loop

The `do while` loop is a variant of the while loop.

The `do while` loop will execute the code block once, before checking if the condition is true, then it will repeat the loop as long as the condition is true.

### Syntax

javascript do {

// code block to be executed

}

while (condition);

Example Code

html

Try it Yourself

> The do while runs at least once, even if the condition is false from the start.
> This is because the code block is executed before the condition is tested:

### Example

javascript do {

text += "The number is " + i;

i++;

}

while (i Do not forget to increase the variable used in the condition, otherwise > the loop will never end!