javascript floating decimal

Question

I have a bit of javascript that dynamically multiplies what users are typing in a text field (by the base var), and displays it in a span. Now I'm just trying to figure out how to get the decimal places of the result to float to 2 places, i.e. 10.00 instead of 10 I found the toFixed function, but can't seem to use it properly... I'd appreciate any help. Thanks

<input id="quantity">
<span id="result"></span> 
<script>

window.onload = function() {
   var base = 3;
   document.getElementById('quantity').onkeyup = function() {
      if(this.value.length == 0) {
         document.getElementById('result').innerHTML = '';
         return;
      }
      var number = parseInt(this.value);
      if(isNaN(number)) return;
      document.getElementById('result').innerHTML = number * base;
   };
   document.getElementById('quantity').onkeyup();
};

Are you sure you want to use parseInt here? It will turn '4.21' into '4'. So the user will be told that 4.21 * 3 = 12.00, which it doesn't. parseFloat will yield a floating point value. — Phil H
– Phil H, Commented Mar 13, 2013 at 16:08

Ankit Jaiswal · Accepted Answer · 2013-03-14 02:56:47Z

1

window.onload = function() { 
 var base = 3; 
 document.getElementById('quantity').onkeyup = function() { 
   if(this.value.length == 0) { 
     document.getElementById('result').innerHTML = ''; 
     return; 
   }    
   if(isNaN(this.value)) 
     return; 
   var number = parseFloat(this.value); 
   var result = (number * base).toFixed(2);
   document.getElementById('result').innerHTML = result; 
   }; 
   document.getElementById('quantity').onkeyup();
};

edited Mar 14, 2013 at 2:56

answered Sep 21, 2010 at 8:35

Ankit Jaiswal

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1 Comment

Phil H Over a year ago

Firstly, can you change parseInt to parseFloat, since the asker is unlikely to want an integer multiplied to 2dp. Also, it might be clearer to have either var result = (number * base).toFixed(2); (expressing it in one statement), or to have two variables and have var preciseResult = number * base; var result = preciseResult.toFixed(2);.

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