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bug(Lifecycle): Lifecycle hooks not called unless defined on the prototype #7270
Description
The lifecycle hooks (component, router) are called if defined on the class, or the function prototype, but are not called if defined in the constructor.
class MyComponent implements OnInit {
ngOnInit() {
// works
}
}
class MyComponent implements OnInit {
ngOnInit: any = () => {
// no TypeScript warning, never called
}
}
function MyComponent() {
}
MyComponent.prototype.ngOnInit = function() {
// works
};
function MyComponent() {
this.ngOnInit = function() {
// never called
};
}I expect the lifecycle hook to be called in either scenario. Is this by design?
cc: @mhevery
Activity
ValeriiVasin commentedon Mar 2, 2016
Have the same issues with lifecycle hooks. That was totally unexpected...
Will it be fixed?
BTW, React lifecycle hooks behave the expected way.
wardbell commentedon Mar 23, 2016
Easy to guess why as it would be safer to analyze a prototype and store the information about the component rather than instantiate one (risk of it doing something in the ctor) to find out what it has.
What use cases argue for this proposal? Isn't it fairly easy to workaround?
mhevery commentedon Mar 25, 2016
Sorry, this is working as intended. The reason for this is that we need to code-gen different code depending if we have such a hook or not. Code-gen can only access the prototype chains, as we can't instantiate/run code. So if you want speed, prototype is the only thing we can look at.
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