Regexp boundary excluding dots, brackets, etc

Question

I have new RegExp(`\\b${escapedQuery}`, "i") regex to search words boundary , where escapedQuery is escaped value after lodash's escapeRegExp function.

const BRANDS = [
  "Alexander McQueen",
  "Alexandre De Paris",
  "alexander.t",
  "A.W.A.K.E. MODE",
  "alexanderwang.t",
  "MARC JACOBS (THE)"
];

function filter(query) {
  return BRANDS.filter((brand) => {
    const escapedQuery = escapeRegExp(query);
    const re = new RegExp(`\\b${escapedQuery}`, "i");
    return re.test(brand);
  });
}

But if I pass a dot or bracket symbol, then I don't get the value I expected.

console.log(filter("al")); // OK [  "Alexander McQueen",  "Alexandre De Paris",  "alexander.t",  "alexanderwang.t"]
console.log(filter("M")); // OK [  "Alexander McQueen", "A.W.A.K.E. MODE", "MARC JACOBS (THE)"]
console.log(filter(".")); // Expected [""] - Actual ["alexander.t", "A.W.A.K.E. MODE", "alexanderwang.t"]
console.log(filter("(")); // OK [""] 
console.log(filter(")")); // Expected [""] - Actual ["MARC JACOBS (THE)"]

Here is Sandbox to better understanding expected and actual results

What needs to be fixed in the expression so that it returns the expected value?

Try ``const re = new RegExp(`(?:\\s|^)${escapedQuery.replace(/[-\/\\^$*+?.()|[\]{}]/g, '\\$&')}`, "i");`` — Wiktor Stribiżew, Sep 16 '22 at 12:36
Thank's, I tried this, but in case when we pass `alexanderwang.` (with dot) the function returns [] and I want it to return `['alexander.t']` — J. Doe, Sep 16 '22 at 13:14
How about [requiring](https://www.regular-expressions.info/lookaround.html) a [word character `\w`](https://stackoverflow.com/a/2998550/5527985) after the boundary: `\\b(?=\\w)${escapedQuery}` — bobble bubble, Sep 16 '22 at 13:26

Wiktor Stribiżew · Accepted Answer · 2022-09-16T14:08:00.377

You can require the first char to be always a word char:

function filter(query) {
    return BRANDS.filter((brand) => {
        const re = new RegExp(`(?=\\w)${query.replace(/[-\/\\^$*+?.()|[\]{}]/g, '\\$&')}`, "i");
        return re.test(brand);
   });
}

See the demo below:

const BRANDS = [
  "Alexander McQueen",
  "Alexandre De Paris",
  "alexander.t",
  "A.W.A.K.E. MODE",
  "alexanderwang.t",
  "MARC JACOBS (THE)"
];

function filter(query) {
  return BRANDS.filter((brand) => {
    const re = new RegExp(`(?=\\w)${query.replace(/[-\/\\^$*+?.()|[\]{}]/g, '\\$&')}`, "i");
    return re.test(brand);
  });
}

console.log(filter("al")); // OK [  "Alexander McQueen",  "Alexandre De Paris",  "alexander.t",  "alexanderwang.t"]
console.log(filter("M")); // OK [  "Alexander McQueen", "A.W.A.K.E. MODE", "MARC JACOBS (THE)"]
console.log(filter(".")); // Expected [""] - Actual ["alexander.t", "A.W.A.K.E. MODE", "alexanderwang.t"]
console.log(filter("(")); // OK [""] 
console.log(filter(")")); // Expected [""] - Actual ["MARC JACOBS (THE)"]

can we modify the regexp so it matched only words from start: BRANDS.push('Arctic Explorer'); filter('ar') //Expected ['Arctic Explorer'] - Actual ['Alexandre De Paris', 'MARC JACOBS (THE)']? — J. Doe, Oct 10 '22 at 11:34
@J.Doe sure, just replace the `(?=\\w)` at the start of the regex with `^`. — Wiktor Stribiżew, Oct 10 '22 at 12:24

Regexp boundary excluding dots, brackets, etc

1 Answers1