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?
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
+1向Jonathan M提供原始方法。由于这是一个明确的货币格式化程序,我继续在输出中添加了货币符号(默认为“$”),并添加了一个默认逗号作为千位分隔符。如果您实际上不需要货币符号(或千位分隔符),只需使用“”(空字符串)作为它的参数。
Number.prototype.formatMoney = function(decPlaces, thouSeparator, decSeparator, currencySymbol) {
// check the args and supply defaults:
decPlaces = isNaN(decPlaces = Math.abs(decPlaces)) ? 2 : decPlaces;
decSeparator = decSeparator == undefined ? "." : decSeparator;
thouSeparator = thouSeparator == undefined ? "," : thouSeparator;
currencySymbol = currencySymbol == undefined ? "$" : currencySymbol;
var n = this,
sign = n < 0 ? "-" : "",
i = parseInt(n = Math.abs(+n || 0).toFixed(decPlaces)) + "",
j = (j = i.length) > 3 ? j % 3 : 0;
return sign + currencySymbol + (j ? i.substr(0, j) + thouSeparator : "") + i.substr(j).replace(/(\d{3})(?=\d)/g, "$1" + thouSeparator) + (decPlaces ? decSeparator + Math.abs(n - i).toFixed(decPlaces).slice(2) : "");
};
其他回答
通常,有多种方法可以执行相同的操作,但我会避免使用Number.prototype.toLocaleString,因为它可以根据用户设置返回不同的值。
我也不建议扩展Number.prototype-扩展原生对象原型是一种糟糕的做法,因为它可能会与其他人的代码(例如库/框架/插件)发生冲突,并且可能与未来的JavaScript实现/版本不兼容。
我认为正则表达式是解决这个问题的最佳方法,下面是我的实现:
/**
* Converts number into currency format
* @param {number} number Number that should be converted.
* @param {string} [decimalSeparator] Decimal separator, defaults to '.'.
* @param {string} [thousandsSeparator] Thousands separator, defaults to ','.
* @param {int} [nDecimalDigits] Number of decimal digits, defaults to `2`.
* @return {string} Formatted string (e.g. numberToCurrency(12345.67) returns '12,345.67')
*/
function numberToCurrency(number, decimalSeparator, thousandsSeparator, nDecimalDigits){
//default values
decimalSeparator = decimalSeparator || '.';
thousandsSeparator = thousandsSeparator || ',';
nDecimalDigits = nDecimalDigits == null? 2 : nDecimalDigits;
var fixed = number.toFixed(nDecimalDigits), //limit/add decimal digits
parts = new RegExp('^(-?\\d{1,3})((?:\\d{3})+)(\\.(\\d{'+ nDecimalDigits +'}))?$').exec( fixed ); //separate begin [$1], middle [$2] and decimal digits [$4]
if(parts){ //number >= 1000 || number <= -1000
return parts[1] + parts[2].replace(/\d{3}/g, thousandsSeparator + '$&') + (parts[4] ? decimalSeparator + parts[4] : '');
}else{
return fixed.replace('.', decimalSeparator);
}
}
YUI代码库使用以下格式:
format: function(nData, oConfig) {
oConfig = oConfig || {};
if(!YAHOO.lang.isNumber(nData)) {
nData *= 1;
}
if(YAHOO.lang.isNumber(nData)) {
var sOutput = nData + "";
var sDecimalSeparator = (oConfig.decimalSeparator) ? oConfig.decimalSeparator : ".";
var nDotIndex;
// Manage decimals
if(YAHOO.lang.isNumber(oConfig.decimalPlaces)) {
// Round to the correct decimal place
var nDecimalPlaces = oConfig.decimalPlaces;
var nDecimal = Math.pow(10, nDecimalPlaces);
sOutput = Math.round(nData*nDecimal)/nDecimal + "";
nDotIndex = sOutput.lastIndexOf(".");
if(nDecimalPlaces > 0) {
// Add the decimal separator
if(nDotIndex < 0) {
sOutput += sDecimalSeparator;
nDotIndex = sOutput.length-1;
}
// Replace the "."
else if(sDecimalSeparator !== "."){
sOutput = sOutput.replace(".",sDecimalSeparator);
}
// Add missing zeros
while((sOutput.length - 1 - nDotIndex) < nDecimalPlaces) {
sOutput += "0";
}
}
}
// Add the thousands separator
if(oConfig.thousandsSeparator) {
var sThousandsSeparator = oConfig.thousandsSeparator;
nDotIndex = sOutput.lastIndexOf(sDecimalSeparator);
nDotIndex = (nDotIndex > -1) ? nDotIndex : sOutput.length;
var sNewOutput = sOutput.substring(nDotIndex);
var nCount = -1;
for (var i=nDotIndex; i>0; i--) {
nCount++;
if ((nCount%3 === 0) && (i !== nDotIndex)) {
sNewOutput = sThousandsSeparator + sNewOutput;
}
sNewOutput = sOutput.charAt(i-1) + sNewOutput;
}
sOutput = sNewOutput;
}
// Prepend prefix
sOutput = (oConfig.prefix) ? oConfig.prefix + sOutput : sOutput;
// Append suffix
sOutput = (oConfig.suffix) ? sOutput + oConfig.suffix : sOutput;
return sOutput;
}
// Still not a number. Just return it unaltered
else {
return nData;
}
}
它需要编辑,因为YUI库是可配置的,比如用“.”替换oConfig.decimalSeparator。
我想要一个自动返回小数部分的普通JavaScript解决方案。
function formatDollar(amount) {
var dollar = Number(amount).toLocaleString("us", "currency");
// Decimals
var arrAmount = dollar.split(".");
if (arrAmount.length==2) {
var decimal = arrAmount[1];
if (decimal.length==1) {
arrAmount[1] += "0";
}
}
if (arrAmount.length==1) {
arrAmount.push("00");
}
return "$" + arrAmount.join(".");
}
console.log(formatDollar("1812.2");
这里有一些解决方案,都通过了测试套件。包括测试套件和基准测试。如果你想复制和粘贴来测试,试试这个要点。
方法0(RegExp)
它是基于VisioN的答案,但如果没有小数点,它会修复。
if (typeof Number.prototype.format === 'undefined') {
Number.prototype.format = function (precision) {
if (!isFinite(this)) {
return this.toString();
}
var a = this.toFixed(precision).split('.');
a[0] = a[0].replace(/\d(?=(\d{3})+$)/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();
这是另一个尝试,只是为了好玩:
function formatDollar(num) {
var p = num.toFixed(2).split(".");
return "$" + p[0].split("").reverse().reduce(function(acc, num, i, orig) {
return num + (num != "-" && i && !(i % 3) ? "," : "") + acc;
}, "") + "." + p[1];
}
还有一些测试:
formatDollar(45664544.23423) // "$45,664,544.23"
formatDollar(45) // "$45.00"
formatDollar(123) // "$123.00"
formatDollar(7824) // "$7,824.00"
formatDollar(1) // "$1.00"
formatDollar(-1345) // "$-1,345.00
formatDollar(-3) // "$-3.00"