我想用JavaScript格式化价格。我想要一个函数，它将浮点作为参数，并返回如下格式的字符串：
"$ 2,500.00"
我该怎么做？
当前回答
这里有一些解决方案，都通过了测试套件。包括测试套件和基准测试。如果你想复制和粘贴来测试，试试这个要点。
方法0（RegExp）
它是基于VisioN的答案，但如果没有小数点，它会修复。
if (typeof Number.prototype.format === 'undefined') {
Number.prototype.format = function (precision) {
if (!isFinite(this)) {
return this.toString();
}
var a = this.toFixed(precision).split('.');
a[0] = a[0].replace(/\d(?=(\d{3})+$)/g, '$&,');
return a.join('.');
}
}
方法1
if (typeof Number.prototype.format === 'undefined') {
Number.prototype.format = function (precision) {
if (!isFinite(this)) {
return this.toString();
}
var a = this.toFixed(precision).split('.'),
// Skip the '-' sign
head = Number(this < 0);
// Skip the digits that's before the first thousands separator
head += (a[0].length - head) % 3 || 3;
a[0] = a[0].slice(0, head) + a[0].slice(head).replace(/\d{3}/g, ',$&');
return a.join('.');
};
}
方法2（拆分到阵列）
if (typeof Number.prototype.format === 'undefined') {
Number.prototype.format = function (precision) {
if (!isFinite(this)) {
return this.toString();
}
var a = this.toFixed(precision).split('.');
a[0] = a[0]
.split('').reverse().join('')
.replace(/\d{3}(?=\d)/g, '$&,')
.split('').reverse().join('');
return a.join('.');
};
}
方法3（循环）
if (typeof Number.prototype.format === 'undefined') {
Number.prototype.format = function (precision) {
if (!isFinite(this)) {
return this.toString();
}
var a = this.toFixed(precision).split('');
a.push('.');
var i = a.indexOf('.') - 3;
while (i > 0 && a[i-1] !== '-') {
a.splice(i, 0, ',');
i -= 3;
}
a.pop();
return a.join('');
};
}
用法示例
console.log('======== Demo ========')
console.log(
(1234567).format(0),
(1234.56).format(2),
(-1234.56).format(0)
);
var n = 0;
for (var i=1; i<20; i++) {
n = (n * 10) + (i % 10)/100;
console.log(n.format(2), (-n).format(2));
}
分离器
如果我们需要自定义千位分隔符或小数分隔符，请使用replace（）：
123456.78.format(2).replace(',', ' ').replace('.', ' ');
测试套件
function assertEqual(a, b) {
if (a !== b) {
throw a + ' !== ' + b;
}
}
function test(format_function) {
console.log(format_function);
assertEqual('NaN', format_function.call(NaN, 0))
assertEqual('Infinity', format_function.call(Infinity, 0))
assertEqual('-Infinity', format_function.call(-Infinity, 0))
assertEqual('0', format_function.call(0, 0))
assertEqual('0.00', format_function.call(0, 2))
assertEqual('1', format_function.call(1, 0))
assertEqual('-1', format_function.call(-1, 0))
// Decimal padding
assertEqual('1.00', format_function.call(1, 2))
assertEqual('-1.00', format_function.call(-1, 2))
// Decimal rounding
assertEqual('0.12', format_function.call(0.123456, 2))
assertEqual('0.1235', format_function.call(0.123456, 4))
assertEqual('-0.12', format_function.call(-0.123456, 2))
assertEqual('-0.1235', format_function.call(-0.123456, 4))
// Thousands separator
assertEqual('1,234', format_function.call(1234.123456, 0))
assertEqual('12,345', format_function.call(12345.123456, 0))
assertEqual('123,456', format_function.call(123456.123456, 0))
assertEqual('1,234,567', format_function.call(1234567.123456, 0))
assertEqual('12,345,678', format_function.call(12345678.123456, 0))
assertEqual('123,456,789', format_function.call(123456789.123456, 0))
assertEqual('-1,234', format_function.call(-1234.123456, 0))
assertEqual('-12,345', format_function.call(-12345.123456, 0))
assertEqual('-123,456', format_function.call(-123456.123456, 0))
assertEqual('-1,234,567', format_function.call(-1234567.123456, 0))
assertEqual('-12,345,678', format_function.call(-12345678.123456, 0))
assertEqual('-123,456,789', format_function.call(-123456789.123456, 0))
// Thousands separator and decimal
assertEqual('1,234.12', format_function.call(1234.123456, 2))
assertEqual('12,345.12', format_function.call(12345.123456, 2))
assertEqual('123,456.12', format_function.call(123456.123456, 2))
assertEqual('1,234,567.12', format_function.call(1234567.123456, 2))
assertEqual('12,345,678.12', format_function.call(12345678.123456, 2))
assertEqual('123,456,789.12', format_function.call(123456789.123456, 2))
assertEqual('-1,234.12', format_function.call(-1234.123456, 2))
assertEqual('-12,345.12', format_function.call(-12345.123456, 2))
assertEqual('-123,456.12', format_function.call(-123456.123456, 2))
assertEqual('-1,234,567.12', format_function.call(-1234567.123456, 2))
assertEqual('-12,345,678.12', format_function.call(-12345678.123456, 2))
assertEqual('-123,456,789.12', format_function.call(-123456789.123456, 2))
}
console.log('======== Testing ========');
test(Number.prototype.format);
test(Number.prototype.format1);
test(Number.prototype.format2);
test(Number.prototype.format3);
基准
function benchmark(f) {
var start = new Date().getTime();
f();
return new Date().getTime() - start;
}
function benchmark_format(f) {
console.log(f);
time = benchmark(function () {
for (var i = 0; i < 100000; i++) {
f.call(123456789, 0);
f.call(123456789, 2);
}
});
console.log(time.format(0) + 'ms');
}
// If not using async, the browser will stop responding while running.
// This will create a new thread to benchmark
async = [];
function next() {
setTimeout(function () {
f = async.shift();
f && f();
next();
}, 10);
}
console.log('======== Benchmark ========');
async.push(function () { benchmark_format(Number.prototype.format); });
next();
其他回答
PHP函数“number_format”有一个JavaScript端口。
我发现它非常有用，因为它易于使用，并且对PHP开发人员来说是可识别的。
function number_format (number, decimals, dec_point, thousands_sep) {
var n = number, prec = decimals;
var toFixedFix = function (n,prec) {
var k = Math.pow(10,prec);
return (Math.round(n*k)/k).toString();
};
n = !isFinite(+n) ? 0 : +n;
prec = !isFinite(+prec) ? 0 : Math.abs(prec);
var sep = (typeof thousands_sep === 'undefined') ? ',' : thousands_sep;
var dec = (typeof dec_point === 'undefined') ? '.' : dec_point;
var s = (prec > 0) ? toFixedFix(n, prec) : toFixedFix(Math.round(n), prec);
// Fix for Internet Explorer parseFloat(0.55).toFixed(0) = 0;
var abs = toFixedFix(Math.abs(n), prec);
var _, i;
if (abs >= 1000) {
_ = abs.split(/\D/);
i = _[0].length % 3 || 3;
_[0] = s.slice(0,i + (n < 0)) +
_[0].slice(i).replace(/(\d{3})/g, sep+'$1');
s = _.join(dec);
} else {
s = s.replace('.', dec);
}
var decPos = s.indexOf(dec);
if (prec >= 1 && decPos !== -1 && (s.length-decPos-1) < prec) {
s += new Array(prec-(s.length-decPos-1)).join(0)+'0';
}
else if (prec >= 1 && decPos === -1) {
s += dec+new Array(prec).join(0)+'0';
}
return s;
}
（原文注释栏，包括以下示例和到期信用）
// Formats a number with grouped thousands
//
// version: 906.1806
// discuss at: http://phpjs.org/functions/number_format
// + original by: Jonas Raoni Soares Silva (http://www.jsfromhell.com)
// + improved by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
// + bugfix by: Michael White (http://getsprink.com)
// + bugfix by: Benjamin Lupton
// + bugfix by: Allan Jensen (http://www.winternet.no)
// + revised by: Jonas Raoni Soares Silva (http://www.jsfromhell.com)
// + bugfix by: Howard Yeend
// + revised by: Luke Smith (http://lucassmith.name)
// + bugfix by: Diogo Resende
// + bugfix by: Rival
// + input by: Kheang Hok Chin (http://www.distantia.ca/)
// + improved by: davook
// + improved by: Brett Zamir (http://brett-zamir.me)
// + input by: Jay Klehr
// + improved by: Brett Zamir (http://brett-zamir.me)
// + input by: Amir Habibi (http://www.residence-mixte.com/)
// + bugfix by: Brett Zamir (http://brett-zamir.me)
// * example 1: number_format(1234.56);
// * returns 1: '1,235'
// * example 2: number_format(1234.56, 2, ',', ' ');
// * returns 2: '1 234,56'
// * example 3: number_format(1234.5678, 2, '.', '');
// * returns 3: '1234.57'
// * example 4: number_format(67, 2, ',', '.');
// * returns 4: '67,00'
// * example 5: number_format(1000);
// * returns 5: '1,000'
// * example 6: number_format(67.311, 2);
// * returns 6: '67.31'
// * example 7: number_format(1000.55, 1);
// * returns 7: '1,000.6'
// * example 8: number_format(67000, 5, ',', '.');
// * returns 8: '67.000,00000'
// * example 9: number_format(0.9, 0);
// * returns 9: '1'
// * example 10: number_format('1.20', 2);
// * returns 10: '1.20'
// * example 11: number_format('1.20', 4);
// * returns 11: '1.2000'
// * example 12: number_format('1.2000', 3);
// * returns 12: '1.200'
function getMoney(A){
var a = new Number(A);
var b = a.toFixed(2); // Get 12345678.90
a = parseInt(a); // Get 12345678
b = (b-a).toPrecision(2); // Get 0.90
b = parseFloat(b).toFixed(2); // In case we get 0.0, we pad it out to 0.00
a = a.toLocaleString(); // Put in commas - Internet Explorer also puts in .00, so we'll get 12,345,678.00
// If Internet Explorer (our number ends in .00)
if(a < 1 && a.lastIndexOf('.00') == (a.length - 3))
{
a = a.substr(0, a.length-3); // Delete the .00
}
return a + b.substr(1); // Remove the 0 from b, then return a + b = 12,345,678.90
}
alert(getMoney(12345678.9));
这适用于Firefox和Internet Explorer。
这可能奏效：
function format_currency(v, number_of_decimals, decimal_separator, currency_sign){
return (isNaN(v)? v : currency_sign + parseInt(v||0).toLocaleString() + decimal_separator + (v*1).toFixed(number_of_decimals).slice(-number_of_decimals));
}
没有循环，没有正则表达式，没有数组，没有奇异条件。
此答案符合以下标准：
不依赖于外部依赖项。支持本地化。有测试/证明。使用简单和最佳的编码实践（没有复杂的正则表达式，使用标准的编码模式）。
此代码基于其他答案中的概念。如果这是一个问题的话，它的执行速度应该是最好的。
var decimalCharacter = Number("1.1").toLocaleString().substr(1,1);
var defaultCurrencyMarker = "$";
function formatCurrency(number, currencyMarker) {
if (typeof number != "number")
number = parseFloat(number, 10);
// if NaN is passed in or comes from the parseFloat, set it to 0.
if (isNaN(number))
number = 0;
var sign = number < 0 ? "-" : "";
number = Math.abs(number); // so our signage goes before the $ symbol.
var integral = Math.floor(number);
var formattedIntegral = integral.toLocaleString();
// IE returns "##.00" while others return "##"
formattedIntegral = formattedIntegral.split(decimalCharacter)[0];
var decimal = Math.round((number - integral) * 100);
return sign + (currencyMarker || defaultCurrencyMarker) +
formattedIntegral +
decimalCharacter +
decimal.toString() + (decimal < 10 ? "0" : "");
}
这些测试仅适用于美国语言环境机器。做出这个决定是为了简单，因为这可能会导致糟糕的输入（错误的自动定位），从而导致糟糕的输出问题。
var tests = [
// [ input, expected result ]
[123123, "$123,123.00"], // no decimal
[123123.123, "$123,123.12"], // decimal rounded down
[123123.126, "$123,123.13"], // decimal rounded up
[123123.4, "$123,123.40"], // single decimal
["123123", "$123,123.00"], // repeat subset of the above using string input.
["123123.123", "$123,123.12"],
["123123.126", "$123,123.13"],
[-123, "-$123.00"] // negatives
];
for (var testIndex=0; testIndex < tests.length; testIndex++) {
var test = tests[testIndex];
var formatted = formatCurrency(test[0]);
if (formatted == test[1]) {
console.log("Test passed, \"" + test[0] + "\" resulted in \"" + formatted + "\"");
} else {
console.error("Test failed. Expected \"" + test[1] + "\", got \"" + formatted + "\"");
}
}
使用正则表达式的较短方法（用于插入空格、逗号或点）：
Number.prototype.toCurrencyString = function(){
return this.toFixed(2).replace(/(\d)(?=(\d{3})+\b)/g, '$1 ');
}
n = 12345678.9;
alert(n.toCurrencyString());
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