var a=1;function fn1(){ alert(a) //undefined var a=2}fn1()alert(a) //1var a=1;function fn1(){ alert(a) //1 a=2}fn1()alert(a) //2var a=1;function fn1(a){ alert(a) //undefined a=2}fn1()alert(a) //1var a=1;function fn1(a){ alert(a) //1 var a=2}fn1(a)alert(a) //1
