Angular & Signals (283 Qs)•Part 9: NgModules, Providers, NgZone & Injector Hierarchies (213 - 255)
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()
js
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.
js
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.
js
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.
js
onInvoke: function(delegate, curr, target, callback, applyThis, applyArgs) {
console.log('the callback will be invoked:', callback);
return delegate.invoke(target, callback, applyThis, applyArgs);
}