纯正则表达式的答案

n.replace(/(\.[0-9]*[1-9])0+$|\.0*$/,'$1');

我想知道为什么没有人给我一个!

如果我们有一个数字的s字符串表示形式，例如我们可以使用number的.toFixed(digits)方法(或任何其他方法)来获得，那么为了从s字符串中删除不重要的末尾零，我们可以使用:

s.replace(/(\.0*|(?<=(\..*))0*)$/, '')

/**********************************
 * Results for various values of s:
 **********************************
 *
 * "0" => 0
 * "0.000" => 0
 * 
 * "10" => 10
 * "100" => 100
 * 
 * "0.100" => 0.1
 * "0.010" => 0.01
 * 
 * "1.101" => 1.101
 * "1.100" => 1.1
 * "1.100010" => 1.10001
 * 
 * "100.11" => 100.11
 * "100.10" => 100.1
 */

replace()中使用的正则表达式解释如下:

In the first place please pay the attention to the | operator inside the regular expression, which stands for "OR", so, the replace() method will remove from s two possible kinds of substring, matched either by the (\.0*)$ part OR by the ((?<=(\..*))0*)$ part. The (\.0*)$ part of regex matches a dot symbol followed by all the zeros and nothing else till to the end of the s. This might be for example 0.0 (.0 is matched & removed), 1.0 (.0 is matched & removed), 0.000 (.000 is matched & removed) or any similar string with all the zeros after the dot, so, all the trailing zeros and the dot itself will be removed if this part of regex will match. The ((?<=(\..*))0*)$ part matches only the trailing zeros (which are located after a dot symbol followed by any number of any symbol before start of the consecutive trailing zeros). This might be for example 0.100 (trailing 00 is matched & removed), 0.010 (last 0 is matched & removed, note that 0.01 part do NOT get matched at all thanks to the "Positive Lookbehind Assertion", i.e. (?<=(\..*)), which is in front of 0* in this part of regex), 1.100010 (last 0 is matched & removed), etc. If neither of the two parts of expression will match, nothing gets removed. This might be for example 100 or 100.11, etc. So, if an input does not have any trailing zeros then it stays unchanged.

更多使用.toFixed(数字)的例子(在下面的例子中使用了字面值“1000.1010”，但我们可以假设变量):

let digits = 0; // Get `digits` from somewhere, for example: user input, some sort of config, etc.

(+"1000.1010").toFixed(digits).replace(/(\.0*|(?<=(\..*))0*)$/, '');
// Result: '1000'

(+"1000.1010").toFixed(digits = 1).replace(/(\.0*|(?<=(\..*))0*)$/, '');
// Result: '1000.1'


(+"1000.1010").toFixed(digits = 2).replace(/(\.0*|(?<=(\..*))0*)$/, '');
// Result: '1000.1'


(+"1000.1010").toFixed(digits = 3).replace(/(\.0*|(?<=(\..*))0*)$/, '');
// Result: '1000.101'


(+"1000.1010").toFixed(digits = 4).replace(/(\.0*|(?<=(\..*))0*)$/, '');
// Result: '1000.101'


(+"1000.1010").toFixed(digits = 5).replace(/(\.0*|(?<=(\..*))0*)$/, '');
// Result: '1000.101'

(+"1000.1010").toFixed(digits = 10).replace(/(\.0*|(?<=(\..*))0*)$/, '');
// Result: '1000.101'

要使用replace()中使用的上述正则表达式，我们可以访问:https://regex101.com/r/owj9fz/1

如果还想处理数字错误，可以使用Intl。NumberFormat或Number.toLocaleString()

new Intl.NumberFormat().format(0.0100) // "0.01"
new Intl.NumberFormat().format(0.010000000000001) // "0.01"
new Intl.NumberFormat().format(0.009999999999999) // "0.01"

console.log((0.0100).toLocaleString()) // "0.01"
console.log((0.010000000000001).toLocaleString()) // "0.01"
console.log((0.009999999999999).toLocaleString()) // "0.01"

我有基本相同的需求，但发现没有内置机制来实现此功能。

除了去掉后面的0之外，我还需要为用户的当前语言环境(即123,456.789)对输出进行四舍五入和格式化。

我在这方面的所有工作都包括在GitHub: https://github.com/dperish/prettyFloat.js上的prettyFloat.js (MIT许可)

使用例子:

prettyFloat(1.111001, 3) // "1.111"
prettyFloat(1.111001, 4) // "1.111"
prettyFloat(1.1111001, 5) // "1.1111"
prettyFloat(1234.5678, 2) // "1234.57"
prettyFloat(1234.5678, 2, true) // "1,234.57" (en-us)

更新- 2018年8月

所有现代浏览器现在都支持ECMAScript国际化API，它提供了语言敏感的字符串比较、数字格式化以及日期和时间格式化。

const formatters = {
    default: new Intl.NumberFormat(),
    currency: new Intl.NumberFormat('en-US', { style: 'currency', currency: 'USD', minimumFractionDigits: 0, maximumFractionDigits: 0 }),
    whole: new Intl.NumberFormat('en-US', { style: 'decimal', minimumFractionDigits: 0, maximumFractionDigits: 0 }),
    oneDecimal: new Intl.NumberFormat('en-US', { style: 'decimal', minimumFractionDigits: 1, maximumFractionDigits: 1 }),
    twoDecimal: new Intl.NumberFormat('en-US', { style: 'decimal', minimumFractionDigits: 2, maximumFractionDigits: 2 })
};

formatters.twoDecimal.format(1234.5678);  // result: "1,234.57"
formatters.currency.format(28761232.291); // result: "$28,761,232"

对于旧的浏览器，您可以使用这个填充:https://cdn.polyfill.io/v2/polyfill.min.js?features=Intl.~locale.en

toFixed方法将在必要时进行适当的舍入。它还将添加尾随零，这并不总是理想的。

(4.55555).toFixed(2);
//-> "4.56"

(4).toFixed(2);
//-> "4.00"

如果将返回值转换为数字，则后面的零将被删除。这是一种比自己进行舍入或截断计算更简单的方法。

+(4.55555).toFixed(2);
//-> 4.56

+(4).toFixed(2);
//-> 4

如果你使用toFixed(n)其中n > 0，一个更简单和稳定(没有更多的浮点运算)的解决方案可以是:

(+n).toFixed(2).replace(/(\.0+|0+)$/, '')

// 0 => 0
// 0.1234 => 0.12
// 0.1001 => 0.1

// 1 => 1
// 1.1234 => 1.12
// 1.1001 => 1.1

// 100 => 100
// 100.1234 => 100.12
// 100.1001 => 100.1

PS:如果你使用toFixed(0)，那么不需要更换。