Help with checking api

Hey, im looking to create a javascript file that is able to check the contents of an api URL such as:

The ending “sgsecret” is the name of the player. I need the file to be able to check if there is content in the URL (meaning if the person’s stream is live or not). Then post the players name only if the player is live. The content of the URL will be empty if the player is not live.

Can anyone point me in the right direction? Or give me an example of how this would be done for one stream? Thanks

No one? =*(