locutus/esm/golang/strings/SplitN.js

Locutus other languages' standard libraries to JavaScript for fun and educational purposes

export function SplitN(s, sep, n) {
    //      discuss at: https://locutus.io/golang/strings/SplitN
    // parity verified: Go 1.23
    //     original by: Kevin van Zonneveld (https://kvz.io)
    //          note 1: Splits into at most n parts. n < 0 means no limit, n == 0 returns [].
    //          note 2: Includes edge cases adapted from Go's src/strings/strings_test.go.
    //       example 1: SplitN('a,b,c', ',', 2)
    //       returns 1: ['a', 'b,c']
    //       example 2: SplitN('a,b,c', ',', -1)
    //       returns 2: ['a', 'b', 'c']
    //       example 3: SplitN('hello', '', 3)
    //       returns 3: ['h', 'e', 'llo']
    //       example 4: SplitN('☺☻☹', '', 17)
    //       returns 4: ['☺', '☻', '☹']
    const value = String(s);
    const delimiter = String(sep);
    const limit = Math.trunc(Number(n));
    if (limit === 0) {
        return [];
    }
    if (delimiter === '') {
        const chars = Array.from(value);
        if (limit < 0) {
            return chars;
        }
        if (limit === 1) {
            return [value];
        }
        if (chars.length < limit) {
            return chars;
        }
        return [...chars.slice(0, limit - 1), chars.slice(limit - 1).join('')];
    }
    if (limit < 0) {
        return value.split(delimiter);
    }
    if (limit === 1) {
        return [value];
    }
    const out = [];
    let remainder = value;
    for (let i = 0; i < limit - 1; i += 1) {
        const index = remainder.indexOf(delimiter);
        if (index < 0) {
            break;
        }
        out.push(remainder.slice(0, index));
        remainder = remainder.slice(index + delimiter.length);
    }
    out.push(remainder);
    return out;
}