Generic definition, the use of

function identity<T>(arg:T):T{
console.log(typeof arg);
return arg;
}
let output1=identity<string>('myString');
let output2=identity('myString');
let output3:number=identity<number>(100);
let output4:number=identity(200);

// set using generic
function loggingIdentity <T> (Arg: the Array <T>): the Array <T> {
the console.log (arg.length);
return Arg;
}
loggingIdentity ([l, 2,3]);

//泛型函数
function identity<T>(arg:T):T{
return arg;
}
let myIdentity:{<T>(arg:T):T}=identity;

//泛型接口
interface GenericIdentityFn<T> {
(arg: T): T;
}
function identity<T>(arg: T): T {
return arg;
}
let myIdentity: GenericIdentityFn<number> = identity;