var用= ， ；一些特殊的表现

       console.log("a" in window);
       console.log("b" in window);
       // var a = b = c =1;//这种写法相当于 var a=1; b=1; c=1;

//        var a = 1;
//        b=1;
//        c=1;

    // var a=1,b=1,c=1;//这种写法相当于var a=1;var b=1;var c=1;
    
    console.log("a" in window);
    console.log("b" in window);
    console.log("c" in window);
    // var a=1;
    // var b=1;
    // var c=1;
    // console.log(a)

    console.log("a" in window);
    console.log("b" in window);
    console.log("c" in window);
    // var a, b,c=1;//这种写法相当于var a;var b;var c=1;
    // var a;
    // var b;
    // var c=1

    console.log("a" in window);
    console.log("b" in window);
    console.log("c" in window);
    // var a;b=c=1;//相当于var a;b=1;c=1;
    // var a;
    // b=1;
    // c=1;