将一个字符串转换为js对象,这个字符串必须是类似数组,object的形式的字符串,例如"[1,2,3]","{a:1,b:2,c:3}"
"[1,2,3,4,5,6]".toObject(); "{a:1,b:2}".toObject();
[1,2,3,4,5,6]; {a:1,b:2}