JavaScript – Convert String to Integer

To convert a string to integer in JavaScript, call parseInt() function and pass the string as argument to it.

Optionally, we may pass the base/radix as second argument to parseInt() function.

parseInt() function returns an integer created from the given string and base/radix.

The syntax to convert a string str to an integer is

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parseInt(str)

The syntax to call parseInt() with base/radix is

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parseInt(str, radix)

Examples

In the following example, we have taken a string in str, and convert this string to integer using parseInt() function.

index.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="utf-8">
</head>
<body>
    <div id="output"></div>
    <script>
        var str = '325';
        var x = parseInt(str);
        document.getElementById('output').innerHTML = 'Integer : ' + x;
    </script>
</body>
</html>

Now, let us give a base value of 8 and parse the integer from given string.

index.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="utf-8">
</head>
<body>
    <div id="output"></div>
    <script>
        var str = '325';
        var radix = 8;
        var x = parseInt(str, radix);
        document.getElementById('output').innerHTML = 'Integer : ' + x;
    </script>
</body>
</html>

The returned value by parseInt() is a decimal value.

Conclusion

In this JavaScript Tutorial, we learned how to convert a string into integer using parseInt() function, with examples.