JavaScript Dynamic Load: Dynamically load JavaScript script files

This object can dynamically load JavaScript script files.

It can take a list of URLs of script files to load dynamically any time even after the page is loaded.

Each script can be loaded by giving a symbolic name that is mapped to the actual script URL.

The object can check if the script was already loaded to prevent duplication.

It appends a script tag to the current page to load the requested script file.

When the script loading is finished, a given callback function may be invoked.