Angular 2 - Components, Bootstrap, and the DOM
Angular is built upon components. The
starting point of an Angular app is the bootstrapping of the initial
parent component. Much like the html DOM tree that starts with an
html element and then branches down from there, Angular runs on a
component tree model.
After Angular loads the first
component with the bootstrap call, it then looks within that
component's html view and sees if it has any nested components. If so,
Angular finds matches and runs the appropriate component code on
those. This repeats for each component down the tree. A component in
Angular is used to render a portion of html and provide functionality to
that portion. It does this through a component class in which you can
define application logic for the component.
For example, you can have a MediaItemComponent that can have a
property named mediaItem that
represents the data for a media item. And that component can also have a
method called onDeleteClick
that could handle raising the delete media item event.
With each component in Angular, you can
specify an html template, the markup that will get rendered, and
through the use of the component class, and how Angular renders the
component, you can display the data for the mediaItem property in your template. And Angular provides an
easy syntax known as the template syntax, to wire up to DOM events
within your template, so you can wire up the click event on a button to
the onDeleteClick method. You
can even use components within components. This is where the component
tree comes into play. Much like how you write html, creating nested
elements within elements, you can build out your Angular apps by
having components rendering components within their templates. Each
component gets configured with a selector, which tells Angular what markup
element tag to associate the component class logic with. When you build a
component in Angular, you are creating a support for a new custom
element for the DOM.
