CODEWITHSUNDEEP
javascriptregex
n as
n as

Reputation: 619

Is there any easy conversion between common wildcards (e.g. * and ?) and javascript regexp?

* and ? are the easiest for non-programmers to understand, with respect to wildcards; in this case, multiple characters and a single character wildcards, respectively.

If I receive a string, where a "?" could appear in any position of the string (e.g. "sing?" or "spo?ls"), how can I convert the string into a javascript regexp which I then compare against a dictionary list? In the case of "spo?ls", I would expect to match "spools", "spoils", etc.

Ditto for use of "*". Thanks.

Sorry if I was not clear: When I meant common wildcards, common to other environments, not Javascript: so, yes, "?" equals any single character [a-z] and "" equals one or more characters [a-z]. In the case of "", consider "*sing", which would match "arousing", "carousing", etc. Or, "ba*ed", which would match "baked", "banked", or "balanced".

Upvotes: 0

Views: 121

Answers (5)

tenub
tenub

Reputation: 3446

var string = 'spo?ls';
if (string.indexOf('?') !== -1) string = string.replace('?', '[a-zA-Z]');
if (string.indexOf('*') !== -1) string = string.replace('*', '[a-zA-Z]+');
var dictionary = ['spoils', 'spools', 'spoools', 'fools', 'tools'];
var re = new RegExp('^' + string + '$');
var results = dictionary.filter(function(el) {
    return (el.match(re) !== null);
});

console.log(results);
["spoils", "spools"];

Now try with string = 'spo*ls';

console.log(results);
["spoils", "spools", "spoools"];

Upvotes: 0

Álvaro González
Álvaro González

Reputation: 146500

Roughly:

  • * → .* (any character, zero or more)
  • ? → . (any character, exactly one)

You'll also need to ignore case (with the i flag) and ensure nothing else matches (with anchors), e.g.:

  • spo?ls → /^spo.ls$/i

Whatever, I recommend you learn some basics about regular expressions. The MDN documentation is quite good.

P.S. The . metacharacter does not match new lines.

Upvotes: 3

Teifun2
Teifun2

Reputation: 338

Pattern tokenpattern = Pattern.compile("string you get");
Matcher matcher = tokenpattern.matcher(content to check);
matcher.find();

Is this the answer to your question?

As i can see the String you get is already the RegularExpression and you just have to use it as one.

Lg Teifun2

Upvotes: -1

gen_Eric
gen_Eric

Reputation: 227280

In regex the period (.) is used to match "any character".

So you could "convert" "spo?ls" to /spo.ls/.

If you wanted the . to possibly match 0 characters, you could use /spo.?ls/. The ? means "0 or 1 character".

In regex, the * character means "0 or more", and + means 1 or more.

So depending on what you were looking for, "spo*ls" could be converted to /spo.+ls/ or /spo.*ls/.

Upvotes: 1

user229044
user229044

Reputation: 239382

That isn't what ? does. ? is a quantifier, not a wild card.

If you want to match any single character, you need ..

In your case, you can replace all instances of ? with ., and then pass the string to RegExp:

pattern = "spo?ls";

// produces /spo.ls/
regex = RegExp(pattern.replace(/\?/g, '.'));

Ditto *: It's a quantifier, not a wild card. You can do the same for *, except you'd replace all instances of * with .*.

Upvotes: 1

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