How to convert URL parameters to a JavaScript object?

Question

I have a string like this:

abc=foo&def=%5Basf%5D&xyz=5

How can I convert it into a JavaScript object like this?

{
          


        

Answer 1

Building on top of Mike Causer's answer I've made this function which takes into consideration multiple params with the same key (foo=bar&foo=baz) and also comma-separated parameters (foo=bar,baz,bin). It also lets you search for a certain query key.

function getQueryParams(queryKey) {
    var queryString = window.location.search;
    var query = {};
    var pairs = (queryString[0] === '?' ? queryString.substr(1) : queryString).split('&');
    for (var i = 0; i < pairs.length; i++) {
        var pair = pairs[i].split('=');
        var key = decodeURIComponent(pair[0]);
        var value = decodeURIComponent(pair[1] || '');
        // Se possui uma vírgula no valor, converter em um array
        value = (value.indexOf(',') === -1 ? value : value.split(','));

        // Se a key já existe, tratar ela como um array
        if (query[key]) {
            if (query[key].constructor === Array) {
                // Array.concat() faz merge se o valor inserido for um array
                query[key] = query[key].concat(value);
            } else {
                // Se não for um array, criar um array contendo o valor anterior e o novo valor
                query[key] = [query[key], value];
            }
        } else {
            query[key] = value;
        }
    }

    if (typeof queryKey === 'undefined') {
        return query;
    } else {
        return query[queryKey];
    }
}

Example input: foo.html?foo=bar&foo=baz&foo=bez,boz,buz&bar=1,2,3

Example output

{
    foo: ["bar","baz","bez","boz","buz"],
    bar: ["1","2","3"]
}