Floating point inaccuracy with Vue.js during content rendering [duplicate] - html

Question

This question already has answers here:
How to deal with floating point number precision in JavaScript?
(47 answers)
Closed 8 years ago.
I have a large amount of numeric values y in javascript. I want to group them by rounding them down to the nearest multiple of x and convert the result to a string.
How do I get around the annoying floating point precision?
For example:
0.2 + 0.4 = 0.6000000000000001
Two things I have tried:
>>> y = 1.23456789
>>> x = 0.2
>>> parseInt(Math.round(Math.floor(y/x))) * x;
1.2000000000000002
and:
>>> y = 1.23456789
>>> x = 0.2
>>> y - (y % x)
1.2000000000000002

Answer 1

From this post: How to deal with floating point number precision in JavaScript?
You have a few options:
Use a special datatype for decimals, like decimal.js
Format your result to some fixed number of significant digits, like this:
(Math.floor(y/x) * x).toFixed(2)
Convert all your numbers to integers

Answer 2

You could do something like this:
> +(Math.floor(y/x)*x).toFixed(15);
1.2
Edit: It would be better to use big.js.
big.js
A small, fast, easy-to-use library for arbitrary-precision decimal arithmetic.
>> bigX = new Big(x)
>> bigY = new Big(y)
>> bigY.div(bigX).round().times(bigX).toNumber() // => 1.2

Answer 3

> var x = 0.1
> var y = 0.2
> var cf = 10
> x * y
0.020000000000000004
> (x * cf) * (y * cf) / (cf * cf)
0.02
Quick solution:
var _cf = (function() {
function _shift(x) {
var parts = x.toString().split('.');
return (parts.length < 2) ? 1 : Math.pow(10, parts[1].length);
}
return function() {
return Array.prototype.reduce.call(arguments, function (prev, next) { return prev === undefined || next === undefined ? undefined : Math.max(prev, _shift (next)); }, -Infinity);
};
})();
Math.a = function () {
var f = _cf.apply(null, arguments); if(f === undefined) return undefined;
function cb(x, y, i, o) { return x + f * y; }
return Array.prototype.reduce.call(arguments, cb, 0) / f;
};
Math.s = function (l,r) { var f = _cf(l,r); return (l * f - r * f) / f; };
Math.m = function () {
var f = _cf.apply(null, arguments);
function cb(x, y, i, o) { return (x*f) * (y*f) / (f * f); }
return Array.prototype.reduce.call(arguments, cb, 1);
};
Math.d = function (l,r) { var f = _cf(l,r); return (l * f) / (r * f); };
> Math.m(0.1, 0.2)
0.02
You can check the full explanation here.

Answer 4

Check out this link.. It helped me a lot.
http://www.w3schools.com/jsref/jsref_toprecision.asp
The toPrecision(no_of_digits_required) function returns a string so don't forget to use the parseFloat() function to convert to decimal point of required precision.

Answer 5

Tackling this task, I'd first find the number of decimal places in x, then round y accordingly. I'd use:
y.toFixed(x.toString().split(".")[1].length);
It should convert x to a string, split it over the decimal point, find the length of the right part, and then y.toFixed(length) should round y based on that length.