Showing posts with label JavaScript For Loop. Show all posts
Showing posts with label JavaScript For Loop. Show all posts

Tuesday, August 28, 2012

JavaScript For Loop


For Loops will execute a block of code a specified number of times.

JavaScript Loops

Often when you write code, you want the same block of code to run over and over again in a row. Instead of adding several almost equal lines in a script we can use loops to perform a task like this.
In JavaScript, there are two different kind of loops:
  • for - loops through a block of code a specified number of times
  • while - loops through a block of code while a specified condition is true

The for Loop

The for loop is used when you know in advance how many times the script should run.

Syntax

for (variable=startvalue;variable<endvalue;variable=variable+increment)
  {
  code to be executed
  }

Example

The example below defines a loop that starts with i=0. The loop will continue to run as long as i is less than 5. i will increase by 1 each time the loop runs.

Note: The increment parameter could also be negative, and the < could be any comparing statement.

Example

for (i=0; i<5; i++)
  {
  x=x + "The number is " + i + "<br />";
  }

Try it yourself »


The while loop

The while loop will be explained in the next chapter.

More Examples

Looping through HTML headings
Loop through the six different HTML headings.