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<h1>JavaScript For Loop</h1>
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<p class="intro">Loops in JavaScript are used to execute the same block of code
a specified number of times or while a specified condition is true.</p>
<hr />
<h2>Examples</h2>
<p><a target="_blank" href="tryit.asp@filename=tryjs_fornext">For loop</a><br />
How to write a for loop. Use a For loop to run the same block of code a specified number of times.</p>
<p><a target="_blank" href="tryit.asp@filename=tryjs_fornext_header">Looping through HTML headers</a><br />
How to use the for loop to loop through the different HTML headers.</p>
<hr />
<h2>JavaScript Loops</h2>
<p>Very 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.</p>
<p>In JavaScript there are two different kind of loops:</p>
<ul>
<li><b>for </b>- loops through a block of code a specified number of times</li>
<li><b>while </b>- loops through a block of code while a specified condition
is true</li>
</ul>
<hr />
<h2>The for Loop</h2>
<p>The for loop is used when you know in advance how many times the script
should run.</p>
<p><b>Syntax</b></p>
<table class="ex" cellspacing="0" border="1" width="100%" id="table1">
<tr>
<td>
<pre>for (var=startvalue;var<=endvalue;var=var+increment)
{
<i>code to be executed</i>
}
</pre>
</td>
</tr>
</table>
<p><b>Example</b></p>
<p>Explanation: The example below defines a loop that starts with i=0. The loop
will continue to run as long as <b>i</b> is less than, or equal to 10. <b>i</b>
will increase by 1 each time the loop runs.</p>
<p><b>Note:</b> The increment parameter could also be negative, and the <=
could be any comparing statement.</p>
<table class="ex" cellspacing="0" border="1" width="100%" id="table2">
<tr>
<td>
<pre><html>
<body>
<script type="text/javascript">
var i=0;
for (i=0;i<=10;i++)
{
document.write("The number is " + i);
document.write("<br />");
}
</script>
</body>
</html></pre>
</td>
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</table>
<p><b>Result</b></p>
<table class="ex" cellspacing="0" border="1" width="100%" id="table3">
<tr>
<td>
<pre>The number is 0
The number is 1
The number is 2
The number is 3
The number is 4
The number is 5
The number is 6
The number is 7
The number is 8
The number is 9
The number is 10</pre>
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<h2>The while loop</h2>
<p>The while loop will be explained in the next chapter.</p>
<hr />
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