Javascript http_build_query : URLs : PHP functions in JavaScript JAVASCRIPT TUTORIALS

function http_build_query( formdata, numeric_prefix, arg_separator ) {
    // Generates a form-encoded query string from an associative array or object.  
    // 
    // version: 810.114
    // discuss at: http://phpjs.org/functions/http_build_query
    // +   original by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
    // +   improved by: Legaev Andrey
    // +   improved by: Michael White (http://getsprink.com)
    // +   improved by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
    // -    depends on: urlencode
    // *     example 1: http_build_query({foo: 'bar', php: 'hypertext processor', baz: 'boom', cow: 'milk'}, '', '&');
    // *     returns 1: 'foo=bar&php=hypertext+processor&baz=boom&cow=milk'
    // *     example 2: http_build_query({'php': 'hypertext processor', 0: 'foo', 1: 'bar', 2: 'baz', 3: 'boom', 'cow': 'milk'}, 'myvar_');
    // *     returns 2: 'php=hypertext+processor&myvar_0=foo&myvar_1=bar&myvar_2=baz&myvar_3=boom&cow=milk'
    var key, use_val, use_key, i = 0, j=0, tmp_arr = [];

    if (!arg_separator) {
        arg_separator = '&';
    }

    for (key in formdata) {
        use_val = urlencode(formdata[key].toString());
        use_key = urlencode(key);

        if (numeric_prefix && !isNaN(key)) {
            use_key = numeric_prefix + j;
            j++;
        }
        tmp_arr[i++] = use_key + '=' + use_val;
    }

    return tmp_arr.join(arg_separator);
}