js怎麼每隔一秒打印出數字呢？

方法一： 自執行函式

    for (var i=0; i<5; i++) {
      (function (i) {
        setTimeout(() => console.log(i), 1000*i)
      })(i)
    }

方法二：傳址傳遞

    var out = (i) => {
      setTimeout (() => console.log(i), 1000*i)
    }
    for (var i=0; i<5; i++) {
      out(i)
    }

方法三： Promise.all()方法

    var arr = []
    var output = (i) => new Promise(res => {
      setTimeout(()=>{
        console.log(i)
        res()
      }, 1000*i)
    })
    for (var i=0; i<5; i++) {
      arr.push(output(i))
    }
    Promise.all(arr).then(()=> console.log(5))

方法四：async await方法

    var sleep =
 
 () => new Promise (res => setTimeout(res, 1000))
    (async function () {
      for (let i=0; i<5; i++) {
        await sleep()
        console.log(i)
      }
    })()