global variable, local variable
1. var a // global variable funtion aaa(){ var a // local variable } 2. var a // global variable funtion aaa(){ var a //local variable a // global variable because there is no var 3. var a // global variable funtion aaa(){ var a //local variable alert(a) //it returns local because it calls the nearest one 4. var a // global variable funtion aaa(){ alert(a) //it returns global 5. var a // global ..