如何为数据表中的所有按钮自定义页眉和页脚

Question

下面是我的代码。我想在下面的代码中添加自定义页眉和页脚。当我点击pdf按钮时，它会自动下载。但是我想在浏览器中显示这个下载文件。所以我该怎么办？它？

"use strict";

var Child = (function(){

  // base class
  class Parent {
    constructor() {
       this.name = "parent";
    }
    parentHello() {
       console.log("parent hello "+this.name);
    }
  }

  // define Bridge which inherits from Parent
  class Bridge extends Parent {
    constructor() {
       super();
       this.name = "bridge";
    }
    bridgeHello() {
        console.log("bridge hello");
    }
  }
  
  class Child extends Bridge {
    constructor() {
        super();
        this.name = "child";
    }
    hello() {
      console.log('hello');
    }
  }

  return Child;
})();

var x = new Child();

console.log(x);
console.log(x.constructor);
x.hello();
x.bridgeHello();
x.parentHello();