Of the two ways to add click events to a button object, why does one use onclick, and the other uses click?

<button id="btn"></button>
button:
1:
  var btn = document.getElementById("btn");
  btn.onclick = function(){
      alert("HelloWorld");
  }
2:
  function hello() {
      alert("addEventListener()");
  }

  var btn = document.getElementById("btn");
  btn.addEventListener("click", hello, false);

when these two methods add click events to button objects, why does one use onclick and the other uses click ?

Html5 javascript
Aug.17,2021

Hello, landlord! You can refer to this article, Portal . Hope to be helpful to you ~

you call addEventListener to know that you are adding an event
but btn.click = function () {} , how do you know it is an event? Or a normal attribute?
add on to know that it is an event

addEventListener ('click') = onclick

because one is DOM0-level event handling and the other is DOM2-level event handling. About the dom event level, it is mentioned in the Red Treasure Book. You can also take a look at this article: https://blog.csdn.net/secret5.

.

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