Javascript - Loops - Javascript For
|
Temmuz 12, 2011 by Javascript Tutorial
|
|
Article Information
This Javascript tutorial contains and tries to cover following subjects:
- Brief explanation of Javascript FOR loops
- Example to Javascript For
Articles tries to provide answer to following questions and issues:
- How to create a for loop in javascript
- How to make iteration in Javascript
- How to execute a code certain number of times in Javascript
Articles pre-requisites following information:
- General knowledge of variables in Javascript
- General knowledge of functions in Javascript
- General knowledge of Loops
Brief explanation of Javascript For
In this javascript Tutorial, we will try to cover Javascript For loops - iteration subject to understand how to create a Javascript for loop, iterate within the loop with a HTML example.
Like many other languages, FOR is a way for iteration. With creating a javascript FOR loop, we can execute a code certain amount of times where javascript developer knows the amount of execution as fixed. Javascript FOR loop executes a code block fixed number of time. This is opposing of other loop in javascript, the WHILE loop. As far as FOR loop condition checks return TRUE, loops keeps itself executing.
To be practice, lets inspect FOR loop and its parts.
for (initializer variable; condition ; iteration incement)
{
code to execute...
}
Initializer is variable that Javascript FOR loop uses starting loop. Its the number that provides ability to keep track of loop. Condition is conditional test part that FOR checks it for each cycle. Iteration increment is the part that after each execution cycle, its modified. To be practice, lets see for loop with real values.
for(var i=0;i<10;i++)
{
document.write(i);
}
In above code snippet, we created a variable named "i". This is our initialization (starting count of loop). This tells javascript that take the number to its memory, go to right side after semicolon and check condition using value of that number. If condition returns TRUE, then execute code below, and then increase its number by 1 ("i++") section.
Idea behind a for loop is to create a condition, a control number-check it-execute code block if condition is ok-increase control number. Our condition is "i<10". Every successful check - test of condition, code block between curly braces are executed and value of "i" is increased by 1. This means.. when our code is executed 9 times, condition will be false. That guarantees that our code is executed 9 times. Otherwise it would execute itself infinite.
Cycle goes like way.
We could declare javascript initialization variable above of for loop instead. That works too.
Example to Javascript For
In following javascript for, we will create above javascript array in HTML page in javascript block. We will be first declaring an multidimensional array, initialize, assign some values and finally display them in HTML page.
HTML page shows result at the right pane. Our javascript loop iterated for 9 times till "i" is less than "10". Every iteration (cycle), document.write() method displayed the value of "i".
Data Layers
| Area: | programming \ languages \ javascript \ \ \ |
| Ref: | |
| Loc: | articles |
| Tags: | javascript |
|