eventTarget.addEventListener(type, listener[, options])


    type 事件添加新的句柄。 对于每个 type 和每个 capture 选项值,任何给定的 listener 仅添加一次。

    • type <string>
    • listener <Function> | <EventListener>
    • options <Object>
      • once <boolean> When true, the listener is automatically removed when it is first invoked. Default: false.
      • passive <boolean> When true, serves as a hint that the listener will not call the Event object's preventDefault() method. Default: false.
      • capture <boolean> Not directly used by Node.js. Added for API completeness. Default: false.
      • signal <AbortSignal> The listener will be removed when the given AbortSignal object's abort() method is called.

    Adds a new handler for the type event. Any given listener is added only once per type and per capture option value.

    If the once option is true, the listener is removed after the next time a type event is dispatched.

    The capture option is not used by Node.js in any functional way other than tracking registered event listeners per the EventTarget specification. Specifically, the capture option is used as part of the key when registering a listener. Any individual listener may be added once with capture = false, and once with capture = true.

    function handler(event) {}
    
    const target = new EventTarget();
    target.addEventListener('foo', handler, { capture: true });  // first
    target.addEventListener('foo', handler, { capture: false }); // second
    
    // Removes the second instance of handler
    target.removeEventListener('foo', handler);
    
    // Removes the first instance of handler
    target.removeEventListener('foo', handler, { capture: true });