TypeScript--泛型

泛型

聲明一個方法，同時返回string,number類型

問題

function getData1(value:string):string{
    return value;
}
function getData2(value:number):number{
    return value;
}

console.log(getData1('aa'));
console.log(getData2(11));

利用any來解決,但是放棄了類型教驗

function getData(value:any):any{
    return value;
}

console.log(getData('aa'));
console.log(getData(11));

利用泛型

function getData<T>(value:T):T{
    return value;
}

console.log(getData<number>(123));
console.log(getData<string>('aaa'));

獲取數組最小值

未使用泛型

要同時實現string,number,要寫2個類來實現

number

class MinClass{
    public list:number[]=[];
    add(num:number){
        this.list.push(num);
    }
    min():number{
        var minNum = this.list[0];
        for(var i =0;i<this.list.length;i++){
            if(minNum > this.list[i]){
                minNum = this.list[i]
            }
        }
        return minNum;
    }
}


var m = new MinClass();
m.add(1);
m.add(6);
m.add(2);
m.add(11);
console.log(m.min());

string

class MinClass{
    public list:string[]=[];
    add(num:string){
        this.list.push(num);
    }
    min():string{
        var minNum = this.list[0];
        for(var i =0;i<this.list.length;i++){
            if(minNum > this.list[i]){
                minNum = this.list[i]
            }
        }
        return minNum;
    }
}


var m = new MinClass();
m.add('a');
m.add('c');
m.add('b');
console.log(m.min());

泛型

一個類，同時實現string,number

class MinClass<T>{
    public list:T[]=[];
    add(num:T):void{
        this.list.push(num);
    }
    min():T{
        var minNum = this.list[0];
        for(var i =0;i<this.list.length;i++){
            if(minNum > this.list[i]){
                minNum = this.list[i]
            }
        }
        return minNum;
    }
}


var m = new MinClass<number>();
m.add(1);
m.add(6);
m.add(2);
m.add(11);
console.log(m.min());


var s = new MinClass<string>();
s.add('a');
s.add('b');
s.add('f');
s.add('d');
console.log(s.min());