Obtain two decimal places in JavaScript without rounding to the next bigger number

Question

I have this JS code:

var propertyYield = annualRent / propertyValue * 100.0;

In specific scenario the result is 4.999.

So when I do this

propertyYield.toFixed(2)

I'm getting propertyYield of 5.00.

What I want to achieve is to actually get 4.99 instead of 5.00 as rounding to two decimals.

How can I achieve that?

Answer 1

Update: As noted by @kuka this does not work for certain decimal numbers due to floating point error math. Don't use this solution - However I'm leaving it here for documentation sake.

Not sure if I know a library method off hand to do that but quick simple old school solution would be this:

Math.floor(4.999 * 100) / 100.0

Answer 2

You could use Math.floor and some additional arithmetics:

Math.floor(15.7784514000 * 100) / 100

Or convert the number into a string, match the number up to the second decimal place and turn it back into a number:

Number(15.7784514000.toString().match(/^\d+(?:\.\d{0,2})?/))

Then you can still call toFixed to get a string with a fixed number of decimal places.

 var num1 = Math.floor(15.7784514000 * 100) / 100; console.log(num1); var num2 = Number(15.7784514000.toString().match(/^\\d+(?:\\.\\d{0,2})?/)); console.log(num2) console.log(num2.toFixed(2))