循环遍历for-in和for-of

从现象看本质

var objs=[{"name":"alex","age":23},
          {"name":"alex1","age":33},
          {"name":"alex2","age":43}];
for(var d in objs)
{
    console.log(d);
}
for(let d of objs)
{
    console.log(d.name);
}
for(var d in objs)
{
    console.log(objs[d]);
}

结果：