16 Understanding components
This chapter covers
- Defining component classes and templates
- Binding templates to component classes
- Using input and output properties in components
- Styling content generated by components
- Querying content generated by components
Components are directives that have their own templates, rather than relying on content provided from elsewhere. Components have access to all the directive features described in earlier chapters and still have a host element, can still define input and output properties, and so on. But they also define their own content using templates.
It can be easy to underestimate the importance of the template, but attribute and structural directives have limitations. Directives can do useful and powerful work, but they don’t have much insight into the elements they are applied to. Directives are most useful when they are general-purpose tools, such the ngModel directive, which can be applied to any data model property and any form element, without regard to what the data or the element is being used for.