What are the lifecycle hooks of a zone?
There are four lifecycle hooks for asynchronous operations from zone.js.
- onScheduleTask: This hook triggers when a new asynchronous task is scheduled. For example, when you call setTimeout()onScheduleTask: function(delegate, curr, target, task) {console.log('new task is scheduled:', task.type, task.source);return delegate.scheduleTask(target, task);}
- onInvokeTask: This hook triggers when an asynchronous task is about to execute. For example, when the callback of setTimeout() is about to execute.onInvokeTask: function(delegate, curr, target, task, applyThis, applyArgs) {console.log('task will be invoked:', task.type, task.source);return delegate.invokeTask(target, task, applyThis, applyArgs);}
- onHasTask: This hook triggers when the status of one kind of task inside a zone changes from stable(no tasks in the zone) to unstable(a new task is scheduled in the zone) or from unstable to stable.onHasTask: function(delegate, curr, target, hasTaskState) {console.log('task state changed in the zone:', hasTaskState);return delegate.hasTask(target, hasTaskState);}
- onInvoke: This hook triggers when a synchronous function is going to execute in the zone.onInvoke: function(delegate, curr, target, callback, applyThis, applyArgs) {console.log('the callback will be invoked:', callback);return delegate.invoke(target, callback, applyThis, applyArgs);}