Javascript Eval() Function

As its name indicates, Javascript eval function is used to execute javascript source code.

Note: Use of eval method is not advised for the following reasons:

security risk
difficult to debug
creates a new instance of Javascript interpreter on each invocation of eval()

Syntax

var num = 2;
eval("num + 200");

Javascript Eval() Function Example

<!DOCTYPE html>
<html>  
<head>  <!-- www.techstrikers.com -->
<title>My first Javascript code</title>   
</head>  
<body bgcolor="#bnde45">
<fieldset>
<legend>Javascript eval Function</legend>
<script> 

var num = 2;  
document.write(eval("num + 200"));  
document.write("</br>");  
  
var code = '{ foo: 123 }';  
document.write(eval(code)); 
document.write("</br>"); 

eval("var foo = 1")
document.write(foo);  
document.write("</br>");

</script>
</fieldset>
</body>  
</html>

See Live Example

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