locutus/esm/rust/str/splitn.js

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

export function splitn(n, delimiter, str) {
    //      discuss at: https://locutus.io/rust/splitn/
    // parity verified: Rust 1.85
    //     original by: Kevin van Zonneveld (https://kvz.io)
    //          note 1: Produces at most n fields; the last field contains the unsplit remainder.
    //       example 1: splitn(3, ' ', 'Mary had a little lamb')
    //       returns 1: ['Mary', 'had', 'a little lamb']
    //       example 2: splitn(1, 'X', 'abcXdef')
    //       returns 2: ['abcXdef']
    //       example 3: splitn(3, 'X', 'lionXXtigerXleopard')
    //       returns 3: ['lion', '', 'tigerXleopard']
    const limit = Math.trunc(Number(n));
    if (!Number.isFinite(limit) || limit <= 0) {
        return [];
    }
    const source = String(str);
    const value = String(delimiter);
    if (limit === 1) {
        return [source];
    }
    if (value === '') {
        const parts = ['', ...Array.from(source), ''];
        if (parts.length <= limit) {
            return parts;
        }
        return [...parts.slice(0, limit - 1), parts.slice(limit - 1).join('')];
    }
    const out = [];
    let remainder = source;
    for (let i = 0; i < limit - 1; i += 1) {
        const index = remainder.indexOf(value);
        if (index < 0) {
            break;
        }
        out.push(remainder.slice(0, index));
        remainder = remainder.slice(index + value.length);
    }
    out.push(remainder);
    return out;
}