mauss/src/web/query/index.js

lightweight, modular, type-safe utilities

/**
 * Query string decoder (`qsd`) decodes a query string into an object. It accepts a query string with or without the leading `?` and returns a mapped object of decoded query string
 *
 * @param qs query string of a URL with or without the leading `?`
 * @returns mapped object of decoded query string
 */
export function qsd(qs) {
    if (qs[0] === '?')
        qs = qs.slice(1);
    if (!qs)
        return {};
    const dec = (s) => {
        if (!s.trim())
            return '';
        s = decodeURIComponent(s);
        if (['true', 'false'].includes(s))
            return s[0] === 't';
        return Number.isNaN(Number(s)) ? s : Number(s);
    };
    const dqs = {};
    const qar = qs.split('&');
    for (let i = 0; i < qar.length; i++) {
        const [k, v] = qar[i].split('=');
        if (v === undefined)
            continue;
        const item = dqs[k]; // satisfy TS
        if (!dqs[k] && (dqs[k] = dec(v)))
            continue;
        if (!Array.isArray(item))
            dqs[k] = [item];
        dqs[k].push(dec(v));
    }
    return dqs;
}
/**
 * Query string encoder (`qse`) encodes key-value pairs from an object into a query string. It optionally accepts a second argument for a transformer function that will be applied to the final value if it exists, else an empty string will be returned
 *
 * @param bound  object with key-value pair to be updated in the URL, only accepts an object with nullish and primitive literals or an array of those values
 * @param transformer function that is applied to the final string if it exists, useful in cases where we want to add a leading `?` when the query exists but not when it's empty, or when we would like to append another existing query string after only if the output of `qse` exists
 * @returns final query string
 */
export function qse(bound, transformer = (final) => `?${final}`) {
    const enc = encodeURIComponent;
    let final = '';
    for (let [k, v] of Object.entries(bound)) {
        if (v == null || (typeof v === 'string' && !(v = v.trim())))
            continue;
        if ((k = enc(k)) && final)
            final += '&';
        if (Array.isArray(v)) {
            let pointer = 0;
            while (pointer < v.length) {
                if (pointer)
                    final += '&';
                const item = v[pointer++];
                if (item == null)
                    continue;
                final += `${k}=${enc(item)}`;
            }
            continue;
        }
        final += `${k}=${enc(v)}`;
    }
    return final ? transformer(final) : final;
}