你可以使用正则表达式：

You can do it with a regular expression:

x = x.replace(/,([^,]*)$/, ".$1");

该正则表达式匹配逗号，后跟任意数量的文本，不包括逗号。替换字符串只是一个句点，后跟原始最后一个逗号之后的句子。字符串中前面的其他逗号不会受到影响。

That regular expression matches a comma followed by any amount of text not including a comma. The replacement string is just a period followed by whatever it was that came after the original last comma. Other commas preceding it in the string won't be affected.

现在，如果您真的要转换格式为欧洲风格的数字（因为缺少更好的术语） ），你还需要担心。 美国风格编号可以使用逗号的地方中的字符。我想你可能只是想摆脱它们：

Now, if you're really converting numbers formatted in "European style" (for lack of a better term), you're also going to need to worry about the "." characters in places where a "U.S. style" number would have commas. I think you would probably just want to get rid of them:

x = x.replace(/\./g, '');

当你对字符串使用.replace（）函数时，你应该明白它返回修改后的字符串。但是，它不会修改原始字符串，因此声明如下：

When you use the ".replace()" function on a string, you should understand that it returns the modified string. It does not modify the original string, however, so a statement like:

x.replace(/something/, "something else");

对x的值没有影响。