typescript generic

type staffsKeys = {
     name: string, 
     salary: number
}

function getProperty<T extends staffsKeys, K extends keyof staffsKeys>(obj: T, key: K): T[K] {
return obj[key];
}/*
What are Generics?
Generics have been a major feature of strongly typed languages 
like Java and C#. In TypeScript, they allow the types of components 
and functions to be "SPECIFIED LATER" which allows them to be used 
in creating reusable components that can apply to different use cases, 

for example:
*/

function returnInput <Type>(arg: Type): Type {
  return arg;
};
const returnInputStr = returnInput<string>('Foo Bar');
const returnInputNum = returnInput<number>(5);

console.log(returnInputStr); // Foo Bar
console.log(returnInputNum); // 5function identity<T>(arg: T): T {    
    return arg;    
}    
let output1 = identity<string>("myString");    
let output2 = identity<number>( 100 );  
console.log(output1);  
console.log(output2);  function firstElement<Type>(arr: Type[]): Type {
  return arr[0];
}
// s is of type 'string'
const s = firstElement(["a", "b", "c"]);
// n is of type 'number'
const n = firstElement([1, 2, 3]);function identity<Type>(arg: Type): Type {
  return arg;
}
 
let myIdentity: <Input>(arg: Input) => Input = identity;   function identity<T>(arg: T): T {
      return arg;
    }


let fun = identity<string>("hello");
console.log(fun);   

/*T is shorthand for Type, meaning "you can specify the data type later"*/class Greeter<T> {
  greeting: T
  constructor(message: T) {
    this.greeting = message
  }
}

let greeter = new Greeter<string>('Hello, world')function identity<T>(arg: T): T {
  return arg;
}Tryconst clone = <T>(object: T) => {
  const clonedObject: T = JSON.parse(JSON.stringify(object));
  return clonedObject;
};

const obj = {
  a: 1,
  b: {
    c: 3,
  },
};

const obj2 = clone(obj);function firstElement<Type>(arr: Type[]): Type | undefined {
  return arr[0];
}const valueWrapper = <T>(value: T): T[] => {
  return [value];
};

console.log(valueWrapper<number>(10));
TypeScript相关代码片段
