Currently, I am delving into the world of Angular2 and familiarizing myself with working with classes in javascript for the first time.
I'm curious about the significance of using the private parameter in the constructor, as opposed to simply writing it as heroService: HeroService.
constructor(private heroService: HeroService) { }
It seems like a parameter property. Essentially, by adding an access modifier (public/private/protected/readonly) to a constructor parameter, it automatically assigns that parameter to a field with the same name.
According to the documentation:
TypeScript provides a special syntax for converting a constructor parameter into a class property with identical name and value. These are known as parameter properties and can be created by prefixing a constructor argument with one of the visibility modifiers: public, private, protected, or readonly. The resulting field inherits those modifier(s).
Therefore, the following examples are equivalent:
class Foo {
private bar: string;
constructor(bar: string) {
this.bar = bar;
}
}
class Foo {
constructor(private bar: string) {}
}
In programming, the use of private will limit the scope of a variable to its specific class or function. Public, on the other hand, allows access from outside as long as you have an instance of the class. Protected is crucial for properties within an abstract superclass. My journey with TypeScript began with experimenting on the TypeScript playground page (https://www.typescriptlang.org/play/index.html), which greatly helped me grasp the concept. It's worth noting that TypeScript serves as a more organized version of JavaScript.
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