他们有什么区别？我得意的笑 囧……
1, null vs undefined
2, new Object vs new Object()
3, function foo(){} vs var foo=function foo(){}
4，var a=b=undefined; vs var a,b;
5,
1 function Foo(){
2 return true;
3 }
VS
function Foo(){
return
true;
}
6, var a =[[1,2,3],[1,2,3],[1,2,3]]
a[1][2] VS a[1,2]