- The parseInt() function extracts a whole number ("integer") from text strings starting with a numeric value. It returns NaN ("Not a Number") if it can't:
var num = "10 popular JavaScript methods";
alert( parseInt(num) ); // 10Tip: check returned values with isNaN() to avoid parsing errors.
- JavaScript fails if the string doesn't start with a number. Work around that with a regular expression and the replace() method to remove the first non-digit characters:
var num = "I learn 10 popular JavaScript methods"; // would return NaN
num = num.replace( /^\D+/, "" ); // Delete non-numbers from start
alert( parseInt(num) ); // 10! - Pass an optional second argument as base in which to extract (base 10 assumed). Let's convert an HTML color code triplet to RGB:
var color = "FF"; // Found in #FF0000 (red)
alert( parseInt( color , 16 ) ); // Returns 255Caveat: without radix as second argument, "0x" is considered base 16, and leading zeros as potential octal numbers (base 8). Explicitly use "parseInt(someNumber,10)" to be safe.
- The PHP equivalent to parseInt() is the intval() function:
$num = '3.14'; // String containing a floating point
echo intval( $num ); // 3 Sister function: parseFloat() extracts floating point values from strings.
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