SOURCE

function test1(){
  var a = {};
a.name = "张三";
console.log("a:"+a.name);
var b = a;
b.name = "李四" ;
console.log("a:"+a.name);
console.log("b:"+b.name);
b = null;
console.log(b);
console.log("a:"+a.name);
}
var a = 0;
function f1(){
  var b = 1;
   function f2(){
     var c = 2;
     b ++;
     console.log(b);
   }
  var f3 =function(){
    console.log("f3");
  }
  return f2();
}
f1();

<h1>
  这里是标题
</h1>