<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>

<body>
    <script>
        const nums = [10, 20, 30, 40, 118]
            /*   let newNums = nums.filter(function(n) {
                  return n < 100
              }) */
        let newNums = nums.map(function(n) {
            return n * 2
        })
        console.log(newNums)

        let total = newNums.reduce(function(preValue, n) {
            return preValue + n
        }, 0)
        console.log(total)
    </script>
</body>

</html>

运行结果