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Javascript allows you to test a block of code for errors using the "try" and "catch" keywords. The try keyword is followed by a block of code that is enclosed within curly braces, followed by the catch keyword which is followed by a block of code that is executed if an error occurs.
The javascript below shows you how to use the try and catch keywords to check for errors.
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"https://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="https://www.w3.org/1999/xhtml" xml:lang="en">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
<title>WebDevelopmentTutorials.com</title>
</head>
<body>
<script type="text/javascript" language="javascript">
<!--
try
{
document.write("This is a test $" + myBankBalance);
}
catch(err)
{
document.write("An error has occurred.");
}
//-->
</script>
</body>
</html>
The javascript above contains an error in the try statement and results in the output below.