lazyMan.js

function lazyMan (name) {
    let man = { name };
    let tasks = [];
    let excute = () => {
      let task = tasks.shift();
      task && task();
    };
    man.talk = () => {
      tasks.push(() => {
        console.log(`Hi! This is ${name}!`);
        excute();
      });
    }
    man.sleep = second => {
      tasks.push(() => {
        window.setTimeout(() => {
          console.log(`Wake up after ${second}`);
          excute();
        }, second * 1000);
      });
      return man;
    }
    man.eat = food => {
      tasks.push(() => {
        console.log(`Eat ${food}~`);
        excute();
      });
      return man;
    }
    man.sleepFirst = second => {
      tasks.unshift(() => {
        window.setTimeout(() => {
          console.log(`Wake up after ${second}`);
          excute();
        }, second * 1000);
      });
      return man;
    };
    man.talk();
    window.setTimeout(excute);
    return man;
  }