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JavaScript parseInt() Function

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Definition and Usage

The parseInt() function parses a string and returns an integer.

The radix parameter is used to specify which numeral system to be used, for example, a radix of 16 (hexadecimal) indicates that the number in the string should be parsed from a hexadecimal number to a decimal number.

If the radix parameter is omitted, JavaScript assumes the following:

Syntax

parseInt(string, radix)

Parameter Description
string Required. The string to be parsed
radix Optional. A number (from 2 to 36) that represents the numeral system to be used

Tips and Notes

Note: Only the first number in the string is returned!

Note: Leading and trailing spaces are allowed.

Note: If the first character cannot be converted to a number, parseInt() returns NaN.

Example

In this example we will use parseInt() to parse different strings:

<script type="text/javascript">

document.write(parseInt("10") + "<br />");
document.write(parseInt("10.00") + "<br />");
document.write(parseInt("10.33") + "<br />");
document.write(parseInt("34 45 66") + "<br />");
document.write(parseInt(" 60 ") + "<br />");
document.write(parseInt("40 years") + "<br />");
document.write(parseInt("He was 40") + "<br />");

document.write("<br />");
document.write(parseInt("10")+ "<br />");
document.write(parseInt("10",10)+ "<br />");
document.write(parseInt("010")+ "<br />");
document.write(parseInt("10",8)+ "<br />");
document.write(parseInt("0x10")+ "<br />");
document.write(parseInt("10",16)+ "<br />");

</script>

The output of the code above will be:

10
10
10
34
60
40
NaN

10
10
8
8
16
16

Try it yourself »
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From http://www.w3schools.com (Copyright Refsnes Data)