A.空字符串 B.0 C.NaN D.undefined E.null F.非空字符串 G.非零的數(shù)值
A.下劃線法(如user_name) B.駝峰法(如userName) C.帕斯卡法(如UserName) D.中文通用表示法(如bianliang)
A.[object String]" B.[String]" C.[object Undefined]" D.[Undefined]"