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SYS_Window.addEventListener() method

Add an event listener

Signature

function addEventListener(
	type: ESYS_WindowEventType,
	listener: (ev: any) => any,
	options?: {
		capture?: undefined | false | true;
		once?: undefined | false | true;
		passive?: undefined | false | true;
		signal?: undefined | AbortSignal;
	},
): ISYS_WindowEventListenerRemovableObject | undefined;

Parameters

Parameter	Type	Description
type	ESYS_WindowEventType	Event type, current support blur focus
listener	(ev: any) => any	Event listener callback
options	{ capture?: undefined | false | true; once?: undefined | false | true; passive?: undefined | false | true; signal?: undefined | AbortSignal }	(Optional) Optional parameters

Returns

ISYS_WindowEventListenerRemovableObject | undefined

Event listener method, used to remove the event listener. If it is undefined, it means creating the event listener failed

Example

// 1. 注册 focus 监听（真实场景由用户切换窗口焦点触发，这里用合成事件模拟）
const removable = eda.sys_Window.addEventListener('focus', () => {
	console.log('窗口获得焦点');
});

// 2. 检查返回的可移除对象，其中的 type 字段记录了监听的事件类型
console.log('监听注册成功：', removable !== undefined, '，事件类型：', removable.type);

// 3. 模拟一次获得焦点事件，回调同步触发
window.dispatchEvent(new Event('focus'));

// 4. 注销监听，恢复原状
eda.sys_Window.removeEventListener(removable);
console.log('监听已注销');