CODEWITHSUNDEEP
javascriptregex
manneJan89
manneJan89

Reputation: 1024

RegExp to match lonely or single uppercase letters

I am trying to create a pipe in angular, but I cannot seem to wrap my head around regular expressions.

I am trying to match only lonely or single uppercase letters and split them. Let us say for instance I have the following:

thisIsAnApple should return [this, Is, An, Apple]

thisIsAString should return [this, Is, AString]

BB88GGFR should return [BB88GGFR]

So the plan is to match a capital letter if it is not accompanied by another capital letter.

This is what I have come up with:

const regExr = new RegExp(/(?=[A-Z])(?![A-Z]{2,})/g);
let split = string.split(regExr);

Upvotes: 1

Views: 144

Answers (1)

Wiktor Stribiżew
Wiktor Stribiżew

Reputation: 626738

You may use

string.split(/(?<=[a-z])(?=[A-Z])/)

Or, to support all Unicode letters:

string.split(/(?<=\p{Ll})(?=\p{Lu})/u)

Basically, you match an empty string between a lowercase and an uppercase letter.

JS demo:

const strings = ['thisIsAnApple', 'thisIsAString', 'BB88GGFR'];
const regex = /(?<=[a-z])(?=[A-Z])/;
for (let s of strings) {
  console.log(s, '=>', s.split(regex));
}

JS demo #2:

const strings = ['thisIsĄnApple', 'этоСТрокаТакая', 'BB88GGFR'];
const regex = /(?<=\p{Ll})(?=\p{Lu})/u;
for (let s of strings) {
  console.log(s, '=>', s.split(regex));
}

Upvotes: 2

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