Timing function packages promise with setInterval

demand

After 1 second print digital 1 to 30, 1 second after the completion of printing digital print 31-60

Code

<script>
        function timer(callback,time)   //这里是封装的函数
        {
            return new Promise((resovle,reject)=>{
                let timerId = setInterval(()=>{
                    // 这里把生成的定时器id传给回调函数，参照前面博客的写法，这种写法需要熟练
                    callback(timerId,resovle);   
                },time);
            });
        }
        let p = timer((timerId,resolve)=>{
            console.log('第一个回调');
            for(let i = 1; i <= 30; i++)
            {
                console.log(i);
                if(i === 30)
                {
                    clearInterval(timerId);
                    resolve();   // 改变第一个promise对象的状态，这样下面就可以收到，进行then处理
                }
            }
        },1000);
        p.then(
            ()=>{
                timer((timerId,resolve)=>{
                    console.log('第二个回调');
                    for(let i = 31; i <= 60; i++)
                    {
                        console.log(i);
                        if(i === 60)
                        {
                            clearInterval(timerId);
                        }
                    }
                },1000);
            }
        );
     </script>