javascript - Math.round() to control decimal places not working - Stack Overflow

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I am trying to round to two decimal places in my code below, however, in many cases the Math Round method to control the number of decimal places does not work for me.

   var newKitAmount = 1;
   var priceNumber =  168;
   var updatedTotal = Math.round(priceNumber * newKitAmount*100)/100;
   alert("total is : " + updatedTotal); //OUTPUTS 168 instead of 168.00

Output generated:168

Desired output:168.00

Example two:5 * 2 = 10

Desired output:10.00

JS Fiddle

What am I doing wrong? How can I fix it?

I am trying to round to two decimal places in my code below, however, in many cases the Math Round method to control the number of decimal places does not work for me.

   var newKitAmount = 1;
   var priceNumber =  168;
   var updatedTotal = Math.round(priceNumber * newKitAmount*100)/100;
   alert("total is : " + updatedTotal); //OUTPUTS 168 instead of 168.00

Output generated:168

Desired output:168.00

Example two:5 * 2 = 10

Desired output:10.00

JS Fiddle

What am I doing wrong? How can I fix it?

• javascript
• formatting

Share Improve this question Follow edited Dec 10, 2012 at 7:36 Peter O. 32.9k1414 gold badges8484 silver badges9797 bronze badges asked Dec 9, 2012 at 14:55 AnchovyLegendAnchovyLegend 12.5k4141 gold badges152152 silver badges240240 bronze badges 5

• 1 You should look at the toFixed() function. – Pointy Commented Dec 9, 2012 at 14:57
• possible duplicate of How to format a float in javascript? – GSerg Commented Dec 9, 2012 at 14:57
• @GSerg I asked nothing about how to format a float. Read the question before posting about duplicates. – AnchovyLegend Commented Dec 9, 2012 at 15:00
• 2 @MHZ This is all about formatting. The rounding works as expected, so your only problem is the proper display, which is formatting. – Olaf Dietsche Commented Dec 9, 2012 at 15:04
• Regardless, posting this is a'duplicate' is wrong, because I asked nothing about floats or formatting, I misunderstood how Math.round is suppose to work. There might be other people out there that expect Math.round() to function as I did, that need to be informed that toFixed() is probably what they're looking for. – AnchovyLegend Commented Dec 9, 2012 at 15:09

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2 Answers 2

Sorted by: Reset to default 9

You should use toFixed if you want to get a fixed number of digits after the dot in your string :

var updatedTotal = (priceNumber * newKitAmount).toFixed(2);

you should use a function to round because of the differences between Firefox and Chrome not rounding the same way with toFixed...

function toFixed(a,b){ //where a is the number and b is the number of decimals
    var m = Math.pow(10,b);
    return Math.round(parseFloat(a)*m)/m;
}

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