1.如果我們在控制臺中執行下列語句，結果分別是什么？為什么？ ``` >>> var a;typeof a; ``` ``` >>> var s = '1s';s++; ``` ``` >>> !!"valse"; ``` ``` >>> typeof -Infinity; ``` ``` >>> 10 % "0"; ``` ``` >>> undefined == null ``` ``` >>> false === ""; ``` ``` >>> typeof "2E+2"; ``` ``` >>> a = 3e+3;a++; ``` 2.執行下面的語句后，v的值會是什么？ ``` >>> var v = v || 10; ``` ``` >>> var v = 100; >>> var v = v || 10; ``` ``` >>> var v = 0; >>> var v = v || 10; ``` ``` >>> var v = null; >>> var v = v || 10; ``` 3.寫一個打印乘法口訣表的腳本程序。利用嵌套循環實現。