Javascript round function does not work

Question

I have a function in JavaScript that rounds numbers.

function roundNumber(num){
    var result = Math.round(num*100)/100;
    return result;
}

alert(roundNumber(5334.5));

//I still get 5334.5 when normally I should get 5335

What am I missing?

Demo: http://jsfiddle.net/HwvX2/

You're dividing the result by 100. Why are you expecting that to be an integer? — Bugs, Feb 06 '14 at 11:26
Your function is a way to truncate to 2 decimal places, but you are expecting to get it to round to the nearest whole number. Bit of a logical error here. — Paddy, Feb 06 '14 at 11:28
You appear to be using code from http://stackoverflow.com/questions/11832914/round-up-to-2-decimal-places-in-javascript which rounds to two decimal places — Ruskin, Feb 06 '14 at 11:30

score 5 · Accepted Answer · edited Feb 06 '14 at 11:27

5

Try to use:

function roundNumber(num){
    var result = Math.round(num);
    return result;
}

alert(roundNumber(5334.5));

edited Feb 06 '14 at 11:27

Danilo Valente

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answered Feb 06 '14 at 11:27

Dima Pog

132
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1

Directly using `Math.round()` makes more sense to me... just saying. – Simone Feb 06 '14 at 11:28

score 3 · Answer 2 · answered Feb 06 '14 at 11:26

3

Try this

alert(Math.round(5334.5));

Demo

answered Feb 06 '14 at 11:26

Amit

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score 2 · Answer 3 · answered Feb 06 '14 at 11:27

2

The answer is correct. You are in effect rounding to 2 decimal places. Should be:

Math.round(num);

answered Feb 06 '14 at 11:27

Ruskin

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score 2 · Answer 4 · answered Feb 06 '14 at 11:49

I think this is one of those times where you want to override the default behaviour, Math.round is a great method but sometimes that wheel just isn't round enough. Here's what you could do:

Math.round = function (x) {
      if (parseInt((x + 0.5).toString().split(".")[0], 10) > parseInt(x.toString().split(".")[0], 10)) {
              return parseInt((x + 1).toString().split(".")[0], 10);
       } else {
              return parseInt(x.toString().split(".")[0], 10);
      }
};

score 1 · Answer 5 · answered Feb 06 '14 at 11:26

1

Use right brackets :

 var result = Math.round(num);

Demo : http://jsbin.com/tibo/1/

answered Feb 06 '14 at 11:26

Roy M J

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Why do you multiply by `100` and then divide by `100`? – Danilo Valente Feb 06 '14 at 11:27
1

@DaniloValente : OP's original question.. I just copied the same.. Need a coffeee.. arg..:) – Roy M J Feb 06 '14 at 11:28

score 0 · Answer 6 · answered Feb 06 '14 at 11:27

0

should be Math.round((num*100)/100)

answered Feb 06 '14 at 11:27

Chris

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score 0 · Answer 7 · answered Feb 06 '14 at 11:30

0

Just modify your codes with this line ::

       var result = Math.round(num);

answered Feb 06 '14 at 11:30

Charles Stevens

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Javascript round function does not work

7 Answers7