The JavaScript eval() is used to execute an argument. The code gets execute slower when the eval() method is used. It also has security implementations since it has a different scope of execution.
Example
Here’s how you can implement eval() function −
<html>
<body>
<script>
var a = 30;
var b = 12;
var res1 = eval("a * b") + "<br>";
var res2 = eval("5 + 10") + "<br>";
document.write(res1);
document.write(res2);
</script>
</body>
</html>