A.trimStart()消除字符串尾部的空格 B.trimEnd()消除头部的空格 C.trimStart()和trimEnd()这两个方法会将原字符串修改 D.trimLeft()是trimStart()的别名,trimRight()是trimEnd()的别名
A.0123456789’ B.0123456abc’ C.abc0123456’ D.abcabcabc0’
A.返回"" B.返回"na" C.返回"an" D.报错(RangeError)