Xchars.js

What is the minimum subset of characters required to run any JavaScript code ?

• 6 characters, JSFuck charset: [()!+]
• 5 characters with pipeline operator proposal: [+|>]
• 5 characters with DOM and custom script id: [+=_]
• 5 characters with DOM and jQuery UI: [+=$]
• Obfuscation challenge, no + sign allowed