CODEWITHSUNDEEP
javascriptjquery
Maniaque
Maniaque

Reputation: 761

javascript: rounding a float UP to nearest .25 (or whatever...)

All answers I can find are rounding to nearest, not up to the value... for example

1.0005 => 1.25  (not 1.00)
1.9   => 2.00
2.10 => 2.25
2.59 => 2.75   etc.

would seem to be pretty basic, but this has me stumped. But this has to round up, not to nearest, which is a relatively easy thing to do.

Upvotes: 8

Views: 3872

Answers (4)

hasbi
hasbi

Reputation: 520

Other divide and multiply will not work for some values such as 1.59 You can try customRound function

function customRound(x) {
    var rest = x - Math.floor(x)

    if (rest >= 0.875) {
        return Math.floor(x) + 1
    } else if (rest >= 0.625) {
        return Math.floor(x) + 0.75
    } else if (rest >= 0.375) {
        return Math.floor(x) + 0.50
    }  else if (rest >= 0.125){
        return Math.floor(x) + 0.25
    } else {
        return Math.floor(x)
    }
}

Upvotes: 0

Hatchet
Hatchet

Reputation: 5428

Divide the number by 0.25 (or whatever fraction you want to round nearest to).

Round up to nearest whole number.

Multiply result by 0.25.

Math.ceil(1.0005 / 0.25) * 0.25
// 1.25

Math.ceil(1.9 / 0.25) * 0.25
// 2

// etc.


function toNearest(num, frac) {
  return Math.ceil(num / frac) * frac;
}

var o = document.getElementById("output");

o.innerHTML += "1.0005 => " + toNearest(1.0005, 0.25) + "<br>";
o.innerHTML += "1.9 => " + toNearest(1.9, 0.25) + "<br>";
o.innerHTML += "2.10 => " + toNearest(2.10, 0.25) + "<br>";
o.innerHTML += "2.59 => " + toNearest(2.59, 0.25);
<div id="output"></div>

Upvotes: 20

Nina Scholz
Nina Scholz

Reputation: 386578

Just multilpy by 4 and take the ceiled value with 4 times.

var values = [1.0005, 1.9, 2.10, 2.59],
    round = values.map(function (a) { return Math.ceil(a * 4) / 4; });

document.write('<pre>' + JSON.stringify(round, 0, 4) + '</pre>');

Upvotes: 1

Andrew Ngo
Andrew Ngo

Reputation: 762

Multiply the number by 4, use Math.ceil on the result and then divide that number by 4.

Upvotes: 1

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