Strict Mode : Strict mode is a way to introduce additional run-time constraints and error-checking into your code.
Typed Arrays : You can use typed arrays to handle binary data from sources such as network protocols, binary file formats, and raw graphics buffers.
The Internet Explorer Web Workers API provides a way to add background workers that run in parallel with the main page. For more information, see About Web workers.
The async attribute of the script element. When this attribute is set to true, the script is executed while the page is being parsed. For more information, see async attribute.