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<h1>JavaScript Throw Statement</h1>
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<p class="intro">The throw statement allows you to create an
exception.</p>
<hr />
<h2>Examples</h2>
<p><a target="_blank" href="tryit.asp@filename=tryjs_throw">The throw statement</a><br />
How to use the throw statement.</p>
<hr />
<h2>The Throw Statement</h2>
<p>The throw statement allows you to create an exception. If you use this
statement together with the try...catch statement, you can control program
flow and generate accurate error messages.</p>
<h3>Syntax</h3>
<table class="ex" cellspacing="0" border="1" width="100%">
<tr>
<td>
<pre>throw(exception)</pre>
</td>
</tr>
</table>
<p>The exception can be a string, integer, Boolean or an object.</p>
<p>Note that throw is written in lowercase letters. Using uppercase
letters will generate a JavaScript error!</p>
<h3>Example 1</h3>
<p>The example below determines the value of a variable called x. If the value
of x is higher than 10 or lower than 0 we are going to throw an error. The error is then caught by the catch argument and the proper
error message is displayed:</p>
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<td>
<pre><html>
<body>
<script type="text/javascript">
var x=prompt("Enter a number between 0 and 10:","");
try
{
if(x>10)
throw "Err1";
else if(x<0)
throw "Err2";
}
catch(er)
{
if(er=="Err1")
alert("Error! The value is too high");
if(er == "Err2")
alert("Error! The value is too low");
}
</script>
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