Using toFixed(2) and math round to get correct rounding
I would like to find a function that will return this kind of formatted values :
1.5555 => 1.55
1.5556 => 1.56
1.5554 => 1.55
1.5651 => 1.56
t开发者_运维知识库oFixed() and math round return this value :
1.5651.fixedTo(2) => 1.57
This will be usefull for money rounding.
How about this?
function wacky_round(number, places) {
var multiplier = Math.pow(10, places+2); // get two extra digits
var fixed = Math.floor(number*multiplier); // convert to integer
fixed += 44; // round down on anything less than x.xxx56
fixed = Math.floor(fixed/100); // chop off last 2 digits
return fixed/Math.pow(10, places);
}
1.5554 => 1.55
1.5555 => 1.55
1.5556 => 1.56
1.5651 => 1.56
So, that works, but I think you'll find that it's not a generally-accepted way to round. http://en.wikipedia.org/wiki/Rounding#Tie-breaking
And standard function
fixedTo = function (number, n) {
var k = Math.pow(10, n);
return (Math.round(number * k) / k);
}
and then call
fixedTo(1.5555, 2) // 1.56
fixedTo(1.5555, 2) // 1.556
fixedTo(0.615, 2) // 0.62
You can use the native Number.toFixed() method.
parseFloat(10.159.toFixed(2))
The above returns 10.16. Number.toFixed() returns a string, so I use parseFloat to convert it to a number.
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