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JavaScript Statement: throw

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In JavaScript, the throw statement (often used in conjunction with the try … catch statement) implements error handling. It throws an exception (technically an Error object).

 

The exception can be specified as just some text (e.g. throw "Error") or a number (e.g. throw 100) or more generally an error object, e.g. throw new Error(100,"Error").

 

EXAMPLE:


HTML USED IN THIS EXAMPLE:
<!DOCTYPE html>
<html> <!-- Copyright (c) Nematrian Limited 2018 -->
<head>
<style>
table,th,tr,td {border: 1px solid black; border-collapse: collapse;}
</style>
</head>
<body>
<table>
<tr>
<th>Example</th>
<th>Resulting value of <code>x</code></th>
</tr>
<tr>
<td><code id="Example"></code></td>
<td><code id="Result"></code></td>
</tr>
</table>

<script>
function crSp(n) { return '<br>' + ('&nbsp;').repeat(n) }
var x = "";
try {
  throw new Error(200,"random error");
}
catch(e) { x = e.message; }
document.getElementById("Example").innerHTML =
     'var x = "";'
     + crSp(0) + 'try {'
     + crSp(2) + 'throw new Error(200,"random error");'
     + crSp(0) + '}'
     + crSp(0) + 'catch(e) { x = e.message; }'
document.getElementById("Result").innerHTML = x;
</script>

</body>
</html>


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