Javascript: Cast Math.sqrt to int?

Question

I've searched through google (maybe I didn't look hard enough) but I could not find how to turn Math.sqrt into an int.

I want to use Math.sqrt for a for loop and I guess I need it as an int but I can't seem to figure out how to cast the result to an int. So how do I do it?

I tried something similar to Java:

(int) Math.sqrt(num);

But it didn't work.

Thanks in advance :)

Answer 1

Use Math.round, Math.ceil, or Math.floor depending on your specific rounding needs.

"For rounding numbers to integers one of Math.round, Math.ceil and Math.floor are preferable, and for a desired result that can be expressed as a 32 bit signed integer the bitwise operation described below might also suit."

-http://www.jibbering.com/faq/faq_notes/type_convert.html#tcNumber

Answer 2

Someone suggested parseInt. That goes from a string to an int, but it's easy to turn a float into a string.

parseInt(Math.sqrt(num)+"")

Remember that no matter what you do, JavaScript is always using floats. There is no integer type.

Answer 3

Math.floor will do it. Doubt you even need to go to an integer, though.

Math.floor(Math.sqrt(num));

Answer 4

Using parseInt(Math.sqrt(num)+"") is slower than using Math.round(Math.sqrt(num)). I think it is because in first example you are creating string, parsing integer value of num and rounding it. in second example you just take int and round it.

Answer 5

i know this is an old question, but i figure for anyone finding this later....

i won't reiterate what the other answers say, but a fun little trick you can do is:

Math.sqrt(2); //1.41......
~~Math.sqrt(2); //1

the double bitwise negative drops off anything after the decimal point. i've been told it's slightly faster, but i'm not entirely convinced.

EDIT: as a note this will round toward 0.