8.泛型（generics）

本文主要是介绍8.泛型（generics），希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

//泛型
function echo<T>(arg: T): T {return arg
}
const result = echo(true)function swap<T, U>(tuple: [T, U]): [U, T] {return [tuple[1], tuple[0]]
}
const result2 = swap(['string', 123])//约束泛型
interface IWithLength {length: number
}
function echoWithLength<T extends IWithLength>(arg: T): T {//console.log(arg.length);return arg
}
const str = echoWithLength('str')
const obj = echoWithLength({ length: 10, width: 10 })
const Arr2 = echoWithLength([1, 2, 3])//泛型 类和接口
class Queue<T> {private data = [];push(item: T) {return this.data.push(item)}pop(): T {return this.data.shift()}
}
const queue = new Queue<number>()
queue.push(1)
console.log(queue.pop().toFixed());const queue2 = new Queue<string>()
queue2.push('str')
console.log(queue2.pop().length)//接口
interface KeyPair<T, U> {key: T;value: U;
}
let kp1: KeyPair<number, string> = { key: 123, value: 'str' }
let kp2: KeyPair<string, number> = { key: 'test', value: 123 }let arr: number[] = [1, 2, 3]
let arrtwo: Array<number> = [1, 2, 3]  //定义数组interface IPlus<T> {(a: T, b: T): T
}
function plus(a: number, b: number): number {return a + b
}function connect(a: string, b: string): string {return a + b
}
const a: IPlus<number> = plus
const b: IPlus<string> = connect

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