eventHandler 中的 this 等于 window type ，而不是 element [重复]

Question

我决定将onclick 事件更改为事件侦听器，但遇到了问题。 案例 a 有效，案例 b 无效。调试器显示这等于窗口类型，而不是元素

  testName.setAttribute("onclick", "toggleTestsWindow(this)");

  // b
  testName.addEventListener("click", () => toggleTestsWindow(this));

Answer 1

这就是我通常编写事件监听器的方式：

// Identifies the HTML element
const mySpan = document.getElementById("mySpan");

// Calls `changeColor` whenever `mySpan` receives a click event
mySpan.addEventListener("click", changeColor);

// Defines `changeColor`
function changeColor(event){
  // The listener can automatically have access to the triggering event
  //   (We call it 'event' for our own convenience)

  // The event's `target` property gives us the element where
  //   the event occurred
  const targ = event.target;

  // Makes some visible change to the DOM 
  if(targ.classList.contains("blue")){
    targ.classList.remove("blue");
  }
  else{
    targ.classList.add("blue");
  }
}

.blue { background-color: lightSkyBlue; }

<span id="mySpan">CLICK ME</span>