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SYS_MessageBus.subscribeOnce() method

Private message bus: subscribe to a message once

Signature

function subscribeOnce(topic: string, callbackFn: (message: any) => void): ISYS_MessageBusTask;

Parameters

Parameter	Type	Description
topic	string	Theme
callbackFn	(message: any) => void	Callback after receiving the message

Returns

ISYS_MessageBusTask

Message bus task

Example

// 1. 注册单次订阅
let received = null;
const task = eda.sys_MessageBus.subscribeOnce('嘉立创示例_单次订阅', (message) => {
	received = message;
});

// 2. 发布两条消息：只有第一条触发回调
eda.sys_MessageBus.publish('嘉立创示例_单次订阅', '首次触发');
eda.sys_MessageBus.publish('嘉立创示例_单次订阅', '第二次发布');
console.log('实际收到：', received);

// 3. 消息未到时也可以主动 cancel 放弃等待
task.cancel();
console.log('已清理单次订阅任务');