2018 TypeScript Update(2)Introduction Basic Grammar - Classes and Functions
Classes
http://www.typescriptlang.org/docs/handbook/classes.html
Functions and prototype-based inheritance to build reusable components.
The class Greeter has three members: a property called greeting, a constructor, and a method greet.
Inheritance
Dog extends Animal
Public, Private and Protected Modifiers
In typescript, each member is public by default.
Readonly modifier
class Octopus{
readonly name: string;
readonly numberOfLegs: number = 8;
constructor (theName: string) {
this.name = theName;
}
}
let dad = new Octopus(“Man with 8 legs”);
dad.name = “main with suit”; //error, can not do on readonly
Getter and Setter
class Employee {
private _fullName: string;
get fullName(): string {
return this._fullName;
}
set fullName(newName: string){
..snip...
}
}
let employee = new Employee();
employee.fullName = “Carl Luo”;
Static Properties
Abstract Classes
abstract class may have some implementation
abstract class Animal {
abstract makeSound(): void;
move(): void {
console.log(“rock and roll");
}
}
Functions
http://www.typescriptlang.org/docs/handbook/functions.html
//Named function
function add(x, y) {
return x+y;
}
//Anonymous function
let myAdd = function(x, y) { return x + y; };
We can add types to each of the parameters and then to the function itself to add a return type.
Function Type
let myAdd: (x:number, y: number) => number = function(x: number, y: number): number { return x + y; };
Default and Optional Parameter
function buildName(firstName: string, lastName?: string) {}
function buildName(firstName: string, lastName = “Luo”) {}
Rest Parameters
function buildName(firstName: string, …restOfName: string[]) {}
Generics
http://www.typescriptlang.org/docs/handbook/generics.html
Type Variable
function identity<T>(arg: T): T {
return arg;
}
Generic Classes
class GenericNumber<T> {
zeroValue: T;
add: (x: T, y: T) => T;
}
let myGenericNumber = new GenericNumber<number>();
myGenericNumber.zeroValue = 0;
myGenericNumber.add = function(x, y) { return x+y; };
Enums
http://www.typescriptlang.org/docs/handbook/enums.html
enum Direction { Up, Down, Left, Right }
enum Response {
No = 0,
Yes = 1,
}
function respond(recipient: string, message: Response): void {}
respond(“Princess Caroline”, Response.Yes)
Type Inference http://www.typescriptlang.org/docs/handbook/type-inference.html
Type Compatibility http://www.typescriptlang.org/docs/handbook/type-compatibility.html
Symbols http://www.typescriptlang.org/docs/handbook/symbols.html
References:
http://sillycat.iteye.com/blog/2412076
2018 TypeScript Update(2)Introduction Basic Grammar - Classes and Functions
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