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Essential Angular

You're reading from   Essential Angular Fast paced guide to Front-end web development with Angular

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Product type Paperback
Published in May 2017
Publisher Packt
ISBN-13 9781788293761
Length 108 pages
Edition 1st Edition
Tools
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Authors (3):
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Narwhal Technologies Inc Narwhal Technologies Inc
Author Profile Icon Narwhal Technologies Inc
Narwhal Technologies Inc
Jeff Cross Jeff Cross
Author Profile Icon Jeff Cross
Jeff Cross
Victor Savkin Victor Savkin
Author Profile Icon Victor Savkin
Victor Savkin
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Toc

Advanced topics

Controlling visibility

You can be more specific where you want to get dependencies from. For instance, you can ask for another directive on the same element.

class CustomInputComponent {
constructor(@Self() f: FormatterDirective) {}
}

Or you can ask for a directive in the same template, that is, you can only inject an ancestor directive from the same HTML file.

class CustomInputComponent {
constructor(@Host() f: CustomForm) {}
}

Finally, you can ask to skip the current element, which can be handy for decorating existing providers or building up tree-like structures.

class SomeComponent {
constructor(@SKipSelf() ancestor: SomeComponent) {}
}

Optional dependencies

To mark a dependency as optional, use the Optional decorator.

class Login {
constructor...
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