Question

98

Math.round(num) vs num.toFixed(0) and browser inconsistencies

rated 0 times [ 101] [ 3] / answers: 1 / hits: 94234 / 15 Years ago, thu, february 19, 2009, 12:00:00

Consider the following code:

for (var i = 0; i < 3; i++) {

   var num = i + 0.50;

   var output = num + " " + Math.round(num) + " " + num.toFixed(0);

   alert(output);

}

In Opera 9.63 I get:

0.5 1 0

1.5 2 2

2.5 3 2

In FF 3.03 I get:

0.5 1 1

1.5 2 2

2.5 3 3

In IE 7 I get:

0.5 1 0

1.5 2 2

2.5 3 3

Note the bolded results. Why are this inconsistencies present? Does this mean that toFixed(0) should be avoided? What's the correct way to round a number to the nearest integer?

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cartersinceren

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answered 15 Years ago masonm · Accepted Answer

Edit: To answer your edit, use Math.round. You could also prototype the Number object to have it do your bidding if you prefer that syntax.

Number.prototype.round = function() {

  return Math.round(this);

}

var num = 3.5;

alert(num.round())

I've never used Number.toFixed() before (mostly because most JS libraries provide a toInt() method), but judging by your results I would say it would be more consistent to use the Math methods (round, floor, ceil) then toFixed if cross-browser consistency is what you are looking for.