Javascript 如何将数字格式化为 2 个小数位，但前提是已经有小数位？
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/5623096/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
How do I format a number to 2 decimal places, but only if there are already decimals?
提问by Jamison
I have a jQuery 1.5+ script, and you select a quantity in a drop-down menu (1,2,3, etc) and it multiplies that quantity by $1.50 to show you a total price. Basically - it's multiplying the quantity selected (1, 2, 3, etc) by the base price of $1.50 - BUT - I can't figure out how to display the price correctly with decimals - example: if you select a quantity of 2, the price displays correctly as $3 (no decimals). But, if you choose 1, or 3, the price displays as $1.5 / $4.5 - missing a 0 in the hundredths decimal place.
我有一个 jQuery 1.5+ 脚本，您在下拉菜单（1、2、3 等）中选择一个数量，然后将该数量乘以 1.50 美元以显示总价。基本上 - 它是将所选数量（1、2、3 等）乘以 1.50 美元的基本价格 - 但是 - 我无法弄清楚如何用小数正确显示价格 - 例如：如果您选择数量 2，价格正确显示为 3 美元（无小数）。但是，如果您选择 1 或 3，价格将显示为 1.5 美元 / 4.5 美元 - 小数点后百分之一缺少 0。
Here's the code - any idea how to show a second 0 in the case that there are not already two decimals? $3 should stay as $3, but $4.5 should become $4.50, etc - I can't get it to work without showing ALL numbers to two decimals, and that's where I'm stuck!
这是代码 - 知道如何在没有两位小数的情况下显示第二个 0 吗？3 美元应该保持为 3 美元，但 4.5 美元应该变成 4.50 美元，等等 - 如果不将所有数字显示为两位小数，我就无法让它工作，这就是我被卡住的地方！
<script type='text/javascript'>
$(function() {
$('#myQuantity').change(function() {
var x = $(this).val();
$('#myAmount').text('$'+(x*1.5));// this is the part that isn't displaying decimals correctly!
});
});
</script>
I'm experimenting with something like result = num.toFixed(2); but can't get it to work yet.
我正在尝试诸如 result = num.toFixed(2); 之类的东西。但还不能让它工作。
Thank you Kindly!
非常感谢你！
回答by odrm
This should do the job:
这应该可以完成这项工作：
var formattedNumber = (x * 1.5).toFixed(2).replace(/[.,]00$/, "");
回答by DGV
I suggest:
我建议：
Math.round(floatNumber*100)/100;
It automatically adds 0, 1 or 2 decimal places.
它会自动添加 0、1 或 2 个小数位。
回答by Peeter
Working example: http://jsfiddle.net/peeter/JxPZH/
工作示例：http: //jsfiddle.net/peeter/JxPZH/
$(document).ready(function() {
$('#itemQuantitySelect_3').change(function() {
var itemPrice = 1.50;
var itemQuantity = $(this).val();
var quantityPrice = (itemPrice * itemQuantity);
if(Math.round(quantityPrice) !== quantityPrice) {
quantityPrice = quantityPrice.toFixed(2);
}
$(this).next("span").html("$" + quantityPrice);
});
});<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<form action="/" method="post">
<select id='itemQuantitySelect_3' name="itemQuantity_3">
<option value='1'>1 Item</option>
<option value='2'>2 Items</option>
<option value='3'>3 Items</option>
</select>
<span>.50</span>
</form>回答by Pointy
How about
怎么样
var str = num.toFixed(2).replace(/\.00$/, '');
回答by kennebec
if a number%1 does not return zero, it is not an integer.
如果数字%1 不返回零，则它不是整数。
//var s='123';
var s='1.2';
s=Number(s);
alert(s%1? s.toFixed(2): s);
回答by daCoda
Use this function:
使用这个功能：
//E.g. 0.5 becomes 0.50; 7 stays as 7.
function twoDecimalPlacesIfCents(amount){
return (amount % 1 !== 0) ? amount.toFixed(2) : amount;
}
回答by Gergely Szabó
回答by user2653980
One other possibility, coerce the string into a number and leverage the fact that 0.00 is falsey to determine how it displays:
另一种可能性是，将字符串强制转换为数字，并利用 0.00 为假的事实来确定它的显示方式：
+(1.123456.toFixed(2)) || 0;
>> 1.12
Where as:
然而：
+(0.00123.toFixed(2)) || 0;
>> 0
回答by Orlandster
There's actually a much more dynamic solution to achieve this. This is useful especially when your number of digits will change.
实际上有一个更加动态的解决方案来实现这一点。这在您的位数将改变时尤其有用。
var formattedNumber = (x * 1.5).toFixed(2).replace(/\.0+$|(\.\d*[1-9])(0+)$/, "");
This will end up to this:
这将结束：
+(2.1234).toFixed(2).replace(/\.0+$|(\.\d*[1-9]);
>> 2.12
// but as mentioned it is dynamic
+(2.1234).toFixed(3).replace(/\.0+$|(\.\d*[1-9]);
>> 2.123
+(2).toFixed(3).replace(/\.0+$|(\.\d*[1-9]);
>> 2
