Differences between constructor vs ngOnInit() method

Constructor ngOnInit
Typescript feature nothing to do with Angular One of the Angular life cycle hook method
constructor is transformed to function with the same name as class created ngOnInit being added to prototype of the class created
Called by Javascript Engine Called by Angular
Constructor is automaticlly called at the time of creating object of the class Invoked by Angular when everything in the component is ready
Used for Injecting dependencies Actual business logic performed here
Not everything in component is initialized at the time of invocation Everything is ready at the time of invocation


Thanks to, Angular js Wiki