const nums = [10,20,111,222,444,40,50]

    let funcTotal = nums.filter(function (n) {
        return n < 100
    }).map(function (n) {
      return n * 2
    }).reduce(function (pre,n) {
      return pre + n
    },0)
    console.log('funcTotal ' + funcTotal);

    //使用箭頭函數(shù)
    let arrowTotal = nums.filter(n => n< 100).map( n => n *2 ).reduce((pre,n) => pre + n)
    console.log("arrowTotal " + arrowTotal);