round to nearest .25 javascript

Question

I want to convert all numbers to the nearest .25

So...

5 becomes 5.00
2.25 becomes 2.25
4 becomes 4.00
3.5 becomes 3.50

Thanks

Answer 1

If speed is your concern, note that you can get about a 30% speed improvement by using:

var nearest = 4;
var rounded = number + nearest/2 - (number+nearest/2) % nearest;

From my website: http://phrogz.net/round-to-nearest-via-modulus-division
Performance tests here: http://jsperf.com/round-to-nearest

Answer 2

Here’s an implementation of what rslite said:

var number = 5.12345;
number = (Math.round(number * 4) / 4).toFixed(2);

Answer 3

Multiply by 4, round to integer, divide by 4 and format with two decimals.

Edit Any reason for the downvotes? At least leave a comment to know what should be improved.

Answer 4

Use below function, hope it helps

function roundByQuarter(value) {
    var inv = 1.0 / 0.25;
    return Math.round(value * inv) / inv;
}

Call the function as below, will result the nearest Quarter value, that is it will not return .32, .89, .56 but will return .25, .75, .50 decimals only.

roundByQuarter(2.74) = 2.75

roundByQuarter(2.34) = 2.25

roundByQuarter(2.94) = 3.00

roundByQuarter(2.24) = 2.25

Answer 5

A very good approximation for rounding:

function Rounding (number, precision){

  var newNumber;
  var sNumber = number.toString();

  var increase = precision + sNumber.length - sNumber.indexOf('.') + 1;

  if (number < 0)
    newNumber = (number -  5 * Math.pow(10,-increase));
  else
  newNumber = (number +  5 * Math.pow(10,-increase));

  var multiple = Math.pow(10,precision);
  return Math.round(newNumber * multiple)/multiple;
}

Answer 6

Here is @Gumbo's answer in a form of a function:

var roundNearQtr = function(number) {
  return (Math.round(number * 4) / 4).toFixed(2);
};

You can now make calls:

roundNearQtr(5.12345); // 5.00
roundNearQtr(3.23); // 3.25
roundNearQtr(3.13); // 3.25
roundNearQtr(3.1247); // 3.00