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
}
{
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.
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.
Loop through the six different HTML headings.
