I need to match either of these numbers in a capturing group: 1 2 4 8 16 32 64.

I tried: ([1248\b16\b\b32\b])(.*)$ that didn't work.

let RE = /([1248163264])/

let trues = ["q1", "q2", "q4", "q16", "q32", "q64"].forEach(_ => _.match(RE))
let falses = ["q3", "q13", "q6"].forEach(_ => _.match(RE))

console.log(trues, falses)

CodePudding user response：

This pattern ([1248\b16\b\b32\b])(.*)$ has 2 capture groups, where the first capture group contains a character class that matches 1 of the listed characters.

If you meant to use a word boundary like (1248\b16\b\b32\b) then that would also not match as this is a pattern where all has to match in that order.

There is also no word boundary between 2 digits.

You might use negative lookarounds as digit boundaries instead:

(?<!\d)(?:[1248]|16|32|64)(?!\d)

Regex demo

let RE = /(?<!\d)(?:[1248]|16|32|64)(?!\d)/;

["q1", "q2", "q4", "q16", "q32", "q64"].forEach(s => console.log(`${s} --> ${RE.test(s)}`));
["q3", "q13", "q6"].forEach(s => console.log(`${s} --> ${RE.test(s)}`));