Javascript Regex: replacing the last dot for a comma

问题

I have the following code:

var x = "100.007"
x = String(parseFloat(x).toFixed(2));
return x
=> 100.01

This works awesomely just how I want it to work. I just want a tiny addition, which is something like:

var x = "100,007"
x.replace(",", ".")
x.replace
x = String(parseFloat(x).toFixed(2));
x.replace(".", ",")
return x
=> 100,01

However, this code will replace the first occurrence of the ",", where I want to catch the last one. Any help would be appreciated.

回答1:

You can do it with a regular expression:

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

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.

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, '');

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");

has no effect on the value of "x".

回答2:

You could do it using the lastIndexOf() function to find the last occurrence of the , and replace it.

The alternative is to use a regular expression with the end of line marker:

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

回答3:

You can use lastIndexOf to find the last occurence of ,. Then you can use slice to put the part before and after the , together with a . inbetween.

回答4:

You can use a regexp. You want to replace the last ',', so the basic idea is to replace the ',' for which there's no ',' after.

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

Will return what you want :-).

回答5:

You don't need to worry about whether or not it's the last ".", because there is only one. JavaScript doesn't store numbers internally with comma or dot-delimited sets.

来源：https://stackoverflow.com/questions/4843691/javascript-regex-replacing-the-last-dot-for-a-comma