1 <!DOCTYPE html> 2 <html> 3 <head lang="en"> 4 <meta charset="UTF-8"> 5 <title></title> 6 </head> 7 <body> 8 <script> 9 10 // 1、----------------------------------- 11 12 // var num = 10; 13 // fun(); 14 // function fun(){ 15 // //变量声明提升 值提升变量名，不提升变量值。var num; 16 // console.log(num); 17 // var num = 20; 18 // } 19 //// 2、----------------------------------- 20 // var a = 18; 21 // f1(); 22 // function f1(){ 23 // var b=9; 24 // console.log(a); 25 // console.log(b); 26 // var a = '123'; 27 // } 28 //// 3、----------------------------------- 29 f2(); 30 console.log(cc); 31 console.log(bb); 32 console.log(aa); 33 function f2(){ 34 var aa = bb = cc = 9; 35 console.log(aa); 36 console.log(bb); 37 console.log(cc); 38 } 39 40 41 42 43 44 45 </script> 46 </body> 47 </html>