The Math.trunc()
function returns the integral part of a number by removing any fractional digits.
Math.trunc(x)
x
Unlike other three Math
methods: Math.floor(), Math.ceil() and Math.round(), the way Math.trunc()
works is very simple and straightforward, just truncate the dot and the digits behind it, no matter whether the argument is a positive number or a negative number.
So, if the argument is a positive number, Math.trunc()
is equivalent to Math.floor()
, otherwise Math.trunc()
is equivalent to Math.ceil()
.
Note, the argument passed to this method will be converted to number type implicitly.
Because trunc()
is a static method of Math
, you always use it as Math.trunc()
, rather than as a method of a Math
object you created (Math
is not a constructor).
Math.trunc()
Math.trunc(13.37); // 13 Math.trunc(42.84); // 42 Math.trunc(0.123); // 0 Math.trunc(-0.123); // -0 Math.trunc('-1.123'); // -1 Math.trunc(NaN); // NaN Math.trunc('foo'); // NaN Math.trunc(); // NaN
Math.trunc = Math.trunc || function(x) { return x < 0 ? Math.ceil(x) : Math.floor(x); }
Created by Mozilla Contributors, license: CC-BY-SA 2.5