How to remove trailing decimals without rounding up?

Question

For example, I have a number 123.429. How can I remove the trailing decimals without rounding up to two decimal place. Hence, I need the number to be up to two d.p. i.e 123.42.

Definitely toFixed() method or Math.round(num * 100) / 100 cannot be used in this situation.

Answer 1

The function you want is Math.floor(x) to remove decimals without rounding up (so floor(4.9) = 4).

var number = Math.floor(num * 100) / 100;

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Edit: I want to update my answer because actually, this rounds down with negative numbers:

var Math.floor(-1.456 * 100) / 100;

-1.46

However, since Javascript 6, they have introduced the Math.trunc() function which truncates to an int without rounding, as expected. You can use it the same way as my proposed usage of Math.floor():

var number = Math.trunc(num * 100) / 100;

Alternatively, the parseInt() method proposed by awe works as well, although requires a string allocation.

Answer 2

var number = parseInt('' + (num * 100)) / 100;