Lost in translation - C# regex to JavaScript regex
I'm having some trouble translating my working C# regular expression into JavaScript's regular expression implementation.
Here's the regular expression:
([a-z]+)((\d+)([a-z]+))?,?
When used on "water2cups,flour4cups,salt2teaspoon"
you should get:
[
["water", "2cups", "2", "cups"]
["flout", "4cups", "4", "cups"]
["salt", "2teaspoon", 开发者_如何转开发"2", "teaspoon"]
]
... And it does. In C#. But not in JavaScript.
I know there are some minor differences across implementations. What am I missing to get this expression working in JavaScript?
UpdateI am using the regex like so:
"water2cups,flour4cups,salt2teaspoon".match(/([a-z]+)((\d+)([a-z]+))?,?/g);
Creating the RegExp
You haven't shown how you're creating your Javascript regular expression, e.g., are you using a literal:
var rex = /([a-z]+)((\d+)([a-z]+))?,?/;
or a string
var rex = new RegExp("([a-z]+)((\\d+)([a-z]+))?,?");
If the latter, note that I've escaped the backslash.
Global Flag
By default, Javascript regular expressions are not global, that may be an issue for you. Add the g
flag if you don't already have it:
var rex = /([a-z]+)((\d+)([a-z]+))?,?/g;
or
var rex = new RegExp("([a-z]+)((\\d+)([a-z]+))?,?", "g");
Using RegExp#exec
rather than String#match
Your edit says you're using String#match
to get an array of matches. I have to admit I hardly ever use String#match
(I use RegExp#exec
, as below.) When I use String#match
with your regex, I get...very odd results that vary from browser to browser. Using a RegExp#exec
loop doesn't do that, so that's what I'd do.
Working Example
This code does what you're looking for:
var rex, str, match, index;
rex = /([a-z]+)((\d+)([a-z]+))?,?/g;
str = "water2cups,flour4cups,salt2teaspoon";
rex.lastIndex = 0; // Workaround for bug/issue in some implementations (they cache literal regexes and don't reset the index for you)
while (match = rex.exec(str)) {
log("Matched:");
for (index = 0; index < match.length; ++index) {
log(" match[" + index + "]: |" + match[index] + "|");
}
}
(The log
function just appends text to a div.)
My output for that is:
Matched:
match[0]: |water2cups,|
match[1]: |water|
match[2]: |2cups|
match[3]: |2|
match[4]: |cups|
Matched:
match[0]: |flour4cups,|
match[1]: |flour|
match[2]: |4cups|
match[3]: |4|
match[4]: |cups|
Matched:
match[0]: |salt2teaspoon|
match[1]: |salt|
match[2]: |2teaspoon|
match[3]: |2|
match[4]: |teaspoon|
(Recall that in Javascript, match[0]
will be the entire match; then match[1]
and so on are your capture groups.)
C# had the "@" operator which automatically escapes backslashes (). I do not think that Javascript supports it, so you basically need to "escape" the backslash by putting in another one, so this should do the trick
([a-z]+)((\d+)([a-z]+))?,?
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