Javascript function to recursively build a query string from an object.

toQueryString.js

/**
 * Variation of https://gist.github.com/luk-/2722097
 */
function toQueryString(obj, recursiveKey) {

    if(obj == null || typeof obj !== "object"){
        return "";
    }

    let keys = Object.keys(obj);

    if (keys.length == 0) {
        return "";
    }

    let key;
    let query;
    let value = "";
    let output = [];
    let pattern = /[!'()*]/g;

    keys.forEach(k=>{

        value = obj[k]

        key = k.toString().replace(/[!'()*]/g, escape);

        recursiveKey ? (key = recursiveKey + "[" + key + "]") : "";

         if (typeof value === "object" && value != null) {
                query = toQueryString(value, key);

                if(query){
                    output.push(query);
                }

        } else if(value != null) {
            output.push(
                key + "=" + value.toString().replace(pattern, escape)
            );
        }
    });


    return output.join("&");
}