Typescript decorator is basically used

typescript Class decorator 
1. Class decorator itself is a function 
2. The decorator executes after the decorated class executes 
3. The decorator of the class accepts that the first parameter is a constructor 
4. Multiple decorators perform the sequence , Top to bottom or left to right , The decoration is executed from bottom to top or from right to left 

tsconfig.json Inner opening decorator ：
"experimentalDecorators": true, 
"emitDecoratorMetadata": true,

/*
Decorator implements analog interface request
*/

const RequestDecorotor = (url: string): MethodDecorator => {
    return (...args:any[]) => {
        const [, , descriptor] = args;
        const methods = descriptor.value;
        descriptor.value = () => {
            new Promise((resolve) => {
                setTimeout(() => {
                    resolve({ name: ' Lao Wang ', age: 28,url });
                },200)
            }).then(res => {
                methods(res)
            })
        }
    }
}

class MockRequest {
    @RequestDecorotor('https://xxx.com')
    public resultData(res:any={}) {
        console.log(" Request the results ", res)
        // { name: ' Lao Wang ', age: 28, url: 'https://xxx.com' }
    }
}

new MockRequest().resultData();

/*
Decorator processing error
*/

const errDecorotor: MethodDecorator = (...args:any[]) => {
    const [, , descriptor] = args;
    const methods = descriptor.value;
    descriptor.value = () => {
        try {
            methods();
        } catch (error) {
            // Custom styles and error handling 
            console.log(`%c${error}`, `color:  red;cont-size:50px`);
        }
    }
}

class ErrorDeal {
    @errDecorotor
    public find() {
        throw new Error(' The file you are looking for does not exist ')
    }
    @errDecorotor
    public login() {
        throw new Error(' Your login permission is insufficient ')
    }
}

const err = new ErrorDeal();
err.find();
err.login();

/*
The decorator factory is in ts Use
You can pass parameters to the decorator , for example
*/

const tankDecorotor = (type:string):ClassDecorator => {
    console.log(type)
    if (type === 'Tank3') {
        return (target: Function) => {
            target.prototype.moveTank = () => {
                console.log('moveTank')
            }
        }
    }

    //player3
    return (target:Function) => {
        target.prototype.playerSing = () => {
            console.log('playerSing')
        }
    }
}

@tankDecorotor('Tank3')
class Tank3 {

}

@tankDecorotor('player3')
class Player3{

}

// call 
const t3 = new Tank3();
(<any>t3).moveTank();

const player3 = new Player3();
(<any>player3).playerSing();

/*  
 Print 
Tank3
player3
moveTank
playerSing
*/