题解 | #计时器#

function count(start, end) {
    console.log(start++)
    let timer = setInterval(function () {
        if (start <= end) {
            console.log(start++)
        } else {
            clearInterval(timer)
        }
    }, 100)
    return {
        cancel: function () {
            clearInterval(timer)
        }
    }
}