Split a string on a capital letter or numbers

Question

I was trying to make a pipe in typescript that would split a PascalCase string, but it would be nice if this would also split on digits as well. I would also like it to split on consecutive capital letters. I have this pipe, which works great, except it only works in Chrome and not Firefox, evidently only Chrome supports look backs. How can accomplish this without look backs?

transform(value: string): string {
        let extracted = '';
        if (!value) {
            return extracted;
        }

        const regExSplit = value
            .split(new RegExp('(?<=[a-z])(?=[A-Z])|(?<=[A-Z])(?=[A-Z][a-z])|(?<=[0-9])(?=[A-Z][a-z])|(?<=[a-zA-Z])(?=[0-9])'));
        for (let i = 0; i < regExSplit.length; i++) {
            if (i !== regExSplit.length - 1) {
                extracted += `${regExSplit[i]} `;
            } else {
                extracted += regExSplit[i];
            }
        }

        return extracted;
    }

So for example a string ANet15Amount should be transformed into A Net 15 Amount. This regex above also would split a camelCase string, but that's not necessary to consider.

Answer 1

How about matching by a more basic pattern like this and joining with space.

let str = `ANet15Amount`;

let camel = str.match(/[A-Z]+(?![a-z])|[A-Z]?[a-z]+|\d+/g).join(' ');

console.log(camel);

First I thought of simply [A-Z][a-z]*|\d+ but this would break eg ABCDefg123 into A B C Defg 123 which would be different working to your current function, that transforms to ABC Defg 123.

There is still a little difference. Yours transforms A1B2 to A 1B 2 and this one to A 1 B 2 where I think this one would be more accurate, wouldn't it.

Answer 2

Just replace any uppercase letter [A-Z] or any sequence of digits \d+ with a space plus what we just matched " $1". We skip the first letter so that no space will be added at the begining of the resulting string by adding a negative lookahead on the start of the string (?!^):

// ...

return value.replace(/(?!^)([A-Z]|\d+)/g, " $1");

Example:

let value = "ANet15Amount";

let result = value.replace(/(?!^)([A-Z]|\d+)/g, " $1");

console.log(result);