How can I remove the decimal part from JavaScript number?

Question

I have the results of a division and I wish to discard the decimal portion of the resultant number.

How can I do this?

Answer 1

You could use...

• Math.trunc() (truncate fractional part, also see below)
• Math.floor() (round down)
• Math.ceil() (round up)
• Math.round() (round to nearest integer)

...dependent on how you wanted to remove the decimal.

Math.trunc() isn't supported on all platforms yet (namely IE), but you could easily use a polyfill in the meantime.

Another method of truncating the fractional portion with excellent platform support is by using a bitwise operator (.e.g |0). The side-effect of using a bitwise operator on a number is it will treat its operand as a signed 32bit integer, therefore removing the fractional component. Keep in mind this will also mangle numbers larger than 32 bits.

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You may also be talking about the inaccuracy of decimal rounding with floating point arithmetic.

Required Reading - What Every Computer Scientist Should Know About Floating-Point Arithmetic.