Extract USERID from Facebook via Javascript and write a form for it for a website

DO NOT RESPOND IF YOU DON'T READ THE PROJECT DETAILS. 1. Make a form 2. Ask in the form the USERNAME in Facebook 3. Extract the USER ID of any Facebook user 4. This is done by replacing [login to view URL]<username> into [login to view URL]<username> A text file will show. Example: [login to view URL] will show { "id": "4", "first_name": "Mark", "gender": "male", "last_name": "Zuckerberg", "link": "[login to view URL]", "locale": "en_US", "name": "Mark Zuckerberg", "username": "zuck" } 5. Output should be : "The Facebook ID-number is (...) Now cut and paste this number in one of the boxes below"