A.foo.att B.foo["att"] C.foo{"att"} D.foo["a"+"t"+"t"]
A.var aa; B.var bb = 3;cc = ’good’; C.var dd = ee = 100; D.var ff = 3,gg = 'he's good';
A、var a=0 , b=-0; B、var a=NaN , b=NaN; C、var a=null , b=undefined; D、var a=[] , b=false;