【TS】promise代替回调函数使用

参考：

https://blog.csdn.net/a42626423/article/details/135101768

https://blog.csdn.net/a42626423/article/details/135101768

    fun() {
        return new Promise((resolve, reject) => {
            let succ = Math.random() > 0.5
            setTimeout(() => {
                if (succ) {
                    resolve(null)
                }
                else {
                    reject(null)
                }
            }, 2000)
        });
    }


    test() {
        this.fun().then((data) => {
            //成功处理resolve
        }, (data) => {
            //失败处理reject
        })
        //或者

        this.fun().then((data) => {
            //成功处理
        }).catch((error: Error) => {
            //失败处理
        })
    }
    
    //加载多个
    fun2() {
        let loadArr = []
        return new Promise((resolve, reject) => {
            Promise.all(loadArr).then(() => {
                //loadArr都执行完之后
                resolve(null);
            }).catch((error: Error) => {
                //loadArr出错
                resolve(null);
            })
        });
    }

    //链式调用
    test2() {
        let p = new Promise(resolve => {
            setTimeout(() => {
                resolve("success 1")
            }, 2000)
        })

        p.then((info) => {
            // 此处继续返回一个promise对象，形成链式调用
            return new Promise(resolve => {
                console.log("info = ", info)
                setTimeout(() => {
                    resolve("success 2")
                }, 2000)
            })
        }).then((info) => {
            console.log("info = ", info)
        }).catch((error: Error) => {
            //失败处理
        })
    }