使用 JavaScript 获取数字的小数部分
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Get decimal portion of a number with JavaScript
提问by Oscar
I have float numbers like 3.2and 1.6.
我有像3.2和这样的浮点数1.6。
I need to separate the number into the integer and decimal part. For example, a value of 3.2would be split into two numbers, i.e. 3and 0.2
我需要将数字分成整数和小数部分。例如，一个值3.2将被分成两个数字，即3和0.2
Getting the integer portion is easy:
获取整数部分很容易：
n = Math.floor(n);
But I am having trouble getting the decimal portion. I have tried this:
但是我在获取小数部分时遇到问题。我试过这个：
remainer = n % 2; //obtem a parte decimal do rating
But it does not always work correctly.
但它并不总是能正常工作。
The previous code has the following output:
前面的代码具有以下输出：
n = 3.1 => remainer = 1.1
What I am missing here?
我在这里缺少什么？
回答by Ignacio Vazquez-Abrams
Use 1, not 2.
使用1，不是2。
js> 2.3 % 1
0.2999999999999998
回答by greenimpala
var decimal = n - Math.floor(n)
Although this won't work for minus numbers so we might have to do
虽然这对负数不起作用，所以我们可能不得不这样做
n = Math.abs(n); // Change to positive
var decimal = n - Math.floor(n)
回答by sdleihssirhc
You could convert to string, right?
你可以转换成字符串，对吧？
n = (n + "").split(".");
回答by jomofrodo
How is 0.2999999999999998 an acceptable answer? If I were the asker I would want an answer of .3. What we have here is false precision, and my experiments with floor, %, etc indicate that Javascript is fond of false precision for these operations. So I think the answers that are using conversion to string are on the right track.
0.2999999999999998 如何是可接受的答案？如果我是提问者，我希望得到 0.3 的答案。我们这里有的是错误精度，我对 floor、% 等的实验表明 Javascript 喜欢这些操作的错误精度。所以我认为使用转换为字符串的答案是正确的。
I would do this:
我会这样做：
var decPart = (n+"").split(".")[1];
Specifically, I was using 100233.1 and I wanted the answer ".1".
具体来说，我使用的是 100233.1，我想要答案“.1”。
回答by Zantafio
Here's how I do it, which I think is the most straightforward way to do it:
这是我的做法，我认为这是最直接的方法：
var x = 3.2;
int_part = Math.trunc(x); // returns 3
float_part = Number((x-int_part).toFixed(2)); // return 0.2
回答by Ethan
A simple way of doing it is:
一个简单的方法是：
var x = 3.2;
var decimals = x - Math.floor(x);
console.log(decimals); //Returns 0.20000000000000018Unfortunately, that doesn't return the exact value. However, that is easily fixed:
不幸的是，这不会返回确切的值。但是，这很容易解决：
var x = 3.2;
var decimals = x - Math.floor(x);
console.log(decimals.toFixed(1)); //Returns 0.2You can use this if you don't know the number of decimal places:
如果您不知道小数位数，您可以使用它：
var x = 3.2;
var decimals = x - Math.floor(x);
var decimalPlaces = x.toString().split('.')[1].length;
decimals = decimals.toFixed(decimalPlaces);
console.log(decimals); //Returns 0.2回答by Nurlan
Language independent way:
语言独立方式：
var a = 3.2;
var fract = a * 10 % 10 /10; //0.2
var integr = a - fract; //3
note that it correct only for numbers with one fractioanal lenght )
请注意，它仅适用于具有一个小数长度的数字）
回答by Sheki
You can use parseInt()function to get the integer part than use that to extract the decimal part
您可以使用parseInt()函数来获取整数部分而不是使用它来提取小数部分
var myNumber = 3.2;
var integerPart = parseInt(myNumber);
var decimalPart = myNumber - integerPart;
Or you could use regex like:
或者你可以使用正则表达式，如：
splitFloat = function(n){
const regex = /(\d*)[.,]{1}(\d*)/;
var m;
if ((m = regex.exec(n.toString())) !== null) {
return {
integer:parseInt(m[1]),
decimal:parseFloat(`0.${m[2]}`)
}
}
}
回答by Gabriel Hautclocq
If precision matters and you require consistent results, here are a few propositions that will return the decimal part of any number as a string, including the leading "0.". If you need it as a float, just add var f = parseFloat( result )in the end.
如果精度很重要并且您需要一致的结果，这里有一些命题可以将任何数字的小数部分作为字符串返回，包括前导“0.”。如果您需要它作为浮点数，只需var f = parseFloat( result )在最后添加。
If the decimal part equals zero, "0.0" will be returned. Null, NaN and undefined numbers are not tested.
如果小数部分为零，则返回“0.0”。不测试 Null、NaN 和未定义的数字。
1. String.split
1. 字符串分割
var nstring = (n + ""),
narray = nstring.split("."),
result = "0." + ( narray.length > 1 ? narray[1] : "0" );
2. String.substring, String.indexOf
2. String.substring, String.indexOf
var nstring = (n + ""),
nindex = nstring.indexOf("."),
result = "0." + (nindex > -1 ? nstring.substring(nindex + 1) : "0");
3. Math.floor, Number.toFixed, String.indexOf
3. Math.floor, Number.toFixed, String.indexOf
var nstring = (n + ""),
nindex = nstring.indexOf("."),
result = ( nindex > -1 ? (n - Math.floor(n)).toFixed(nstring.length - nindex - 1) : "0.0");
4. Math.floor, Number.toFixed, String.split
4. Math.floor, Number.toFixed, String.split
var nstring = (n + ""),
narray = nstring.split("."),
result = (narray.length > 1 ? (n - Math.floor(n)).toFixed(narray[1].length) : "0.0");
Here is a jsPerf link: https://jsperf.com/decpart-of-number/
这是一个 jsPerf 链接：https://jsperf.com/decpart-of-number/
We can see that proposition #2 is the fastest.
我们可以看到命题#2 是最快的。
回答by cdmdotnet
The following works regardless of the regional settings for decimal separator... on the condition only one character is used for a separator.
无论小数点分隔符的区域设置如何，以下都有效......条件是仅使用一个字符作为分隔符。
var n = 2015.15;
var integer = Math.floor(n).toString();
var strungNumber = n.toString();
if (integer.length === strungNumber.length)
return "0";
return strungNumber.substring(integer.length + 1);
It ain't pretty, but it's accurate.
它不漂亮，但它是准确的。
