====== Javascript URLSearchParams ======
URLSearchParams is an JavaScript Object that handle the search/query parameters in your URL. Details can be find in https://developer.mozilla.org/en-US/docs/Web/API/URLSearchParams

===== Usage =====
Assume you have the query/search part of the URL. You can create an URLSearchParams object by:
<code>
var paramsString = "q=URLUtils.searchParams&topic=api";
var searchParams = new URLSearchParams(paramsString);

//Iterate the search parameters.
for (let p of searchParams) {
  console.log(p);
}
searchParams.has("topic") === true; // true
searchParams.get("topic") === "api"; // true
</code>

**Note that DO NOT USE THE WHOLE URL as the parameter!** It will not work! Use the search/query part string only! If the string have a leading ?, URLSearchParams will strip it on create.

===== Member Methods =====
Most of the time we use get, has, for loop them through. Here is a list of URLSearchParams methods from https://developer.mozilla.org/en-US/docs/Web/API/URLSearchParams
<code>
URLSearchParams.append()
    Appends a specified key/value pair as a new search parameter.
URLSearchParams.delete()
    Deletes the given search parameter, and its associated value, from the list of all search parameters.
URLSearchParams.entries()
    Returns an iterator allowing iteration through all key/value pairs contained in this object.
URLSearchParams.forEach()
    Allows iteration through all values contained in this object via a callback function.
URLSearchParams.get()
    Returns the first value associated with the given search parameter.
URLSearchParams.getAll()
    Returns all the values associated with a given search parameter.
URLSearchParams.has()
    Returns a Boolean indicating if such a given parameter exists.
URLSearchParams.keys()
    Returns an iterator allowing iteration through all keys of the key/value pairs contained in this object.
URLSearchParams.set()
    Sets the value associated with a given search parameter to the given value. If there are several values, the others are deleted.
URLSearchParams.sort()
    Sorts all key/value pairs, if any, by their keys.
URLSearchParams.toString()
    Returns a string containing a query string suitable for use in a URL.
URLSearchParams.values()
    Returns an iterator allowing iteration through all values of the key/value pairs contained in this object. 
</code>