typeof operator

To see what type of variable something is, use the typeof operator.

Code:

<script type="text/javascript">
//<![CDATA[

var myLiteral = "Hello";
document.write("variable myLiteral has a value of \"", myLiteral, "\" and a type of ", typeof myLiteral, "<br><br>");

var myInteger = 333;
document.write("variable myInteger has a value of ", myInteger, " and a type of ", typeof myInteger, "<br><br>");

var myDollarAmount = 238.54;
document.write("variable myDollarAmount has a value of ", myDollarAmount, " and a type of ", typeof myDollarAmount, "<br><br>");

var myTrueFalseFlag = false;
document.write("variable myTrueFalseFlag has a value of ", myTrueFalseFlag, " and a type of ", typeof myTrueFalseFlag, "<br><br>");

var myEmptyVoid = null;
document.write("variable myEmptyVoid has a value of ", myEmptyVoid, " and a type of ", typeof myEmptyVoid, "<br><br>");

var myParseIntResult = parseInt("eleven");
document.write("variable myParseIntResult has a value of ", myParseIntResult, " and a type of ", typeof myParseIntResult, "<br>");
//]]>
</script>

Output: