Round a number down in JavaScript

Question

I know this maybe very simple and common but I want to know about this calculation:

Example: I have a decimal number 4.716981132075472, but I only need the 4 number, is there any calculation able to do this?

duplicate http://stackoverflow.com/questions/7312468/javascript-round-to-a-number-of-decimal-places-but-strip-extra-zeros ? — ncubica, Jan 09 '15 at 02:07

score 5 · Accepted Answer · answered Jan 09 '15 at 02:06

5

Try round off:

var result = 4.716981132075472 << 0;
alert(result);

OR

var result = Math.floor(4.716981132075472);
alert(result);

answered Jan 09 '15 at 02:06

the first option its really cool.. what the name for do that?? – ncubica Jan 09 '15 at 02:10
@ncubica, `<<` a left-shift bitwise operator – Jan 09 '15 at 02:13
Or `var result = 4.716981132075472 | 0;` – RobG Jan 09 '15 at 02:45

score 3 · Answer 2 · answered Jan 09 '15 at 02:06

3

You are looking for Math.floor() docs here

answered Jan 09 '15 at 02:06

rdubya

MDN is great, but the definitive documentation is here: [*ECMA-262 §15.8.2.9*](http://ecma-international.org/ecma-262/5.1/#sec-15.8.2.9). :-) – RobG Jan 09 '15 at 02:48

score 1 · Answer 3 · answered Jan 09 '15 at 02:06

1

Try Math.floor( 4.716981132075472);. This rounds the number down to the nearest integer, thus solving your problem.

answered Jan 09 '15 at 02:06

DripDrop

3 Answers3