Convert undefined to number, string and Boolean - Javascript Data Type

Javascript examples for Data Type:Data Type Cast

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Introduction

OriginalValueConverted to Number Converted to String Converted to Boolean
undefinedNaN"undefined"false

Demo Code

ResultView the demo in separate window 

<!DOCTYPE html>
<html>
<body>

<p>Converting undefined to other types:</p>

<p id="demo" style="font-family:courier"></p>

<script>
var x = undefined;/*from  w w w. ja  v  a  2s. c  om*/
document.getElementById("demo").innerHTML =
"Number : " + Number(x) + "<br>" +
"String : " + String(x) + "<br>" +
"Boolean: " + Boolean(x);
</script>

</body>
</html>

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