Regex pattern for Pilcrow (¶) or Partial Differential (∂) character

Question

I need to find find/replace or convert pilcrow / partial differential characters in a string as they currently show as �.

What I thought would work but doesn't:

const value = 'Javascript Regex pattern for Pilcrow (¶) or Partial Differential (∂) character';
const matches = value.match(/\u2029/gmi);
console.log(matches);

But returns empty.

To be honest, I'm not even sure how to achieve what I need to do.

Answer 1

The correct Unicode code points are U+00B6 and U+2202, not U+2029. You'll also want to use a [] character range in your expression:

const value = 'Javascript Regex pattern for Pilcrow (¶) or Partial Differential (∂) character';
const matches = value.match(/[\u00B6\u2202]/gmi);
console.log(matches);

Of course, you don't really need \u escapes in the first place:

const value = 'Javascript Regex pattern for Pilcrow (¶) or Partial Differential (∂) character';
const matches = value.match(/[¶∂]/gmi);
console.log(matches);

Last but not least, you say:

they currently show as �.

If that's the case, it's very likely that it isn't properly encoded to begin with. In other words, you won't find ¶ or ∂ because they aren't there. I suggest you address this first.

Answer 2

Use String.prototype.codePointAt to extract the unicode UTF-16 code point and convert it into hex digits sequence.

const toUnicodeCodePointHex = (str) => {
    const codePoint = str.codePointAt(0).toString(16);
    return '\\u' + '0000'.substring(0, 4 - codePoint.length) + codePoint;
};

const value = 'Javascript Regex pattern for Pilcrow (¶) or Partial Differential (∂) character';

const re = new RegExp(['¶', '∂'].map((item) => toUnicodeCodePointHex(item)).join('|'), 'ig');

const matches = value.match(re);
console.log(matches);

See this very nice article by Mathias Bynens.

Answer 3

You can find them by hex or octal value:

const matches = value.match(/\u00B6|\u2202/g);

Regex for each:

Pilcrow: \u00B6 or \xB6 or \266

Partial Differential: \u2202