数组拍平.html

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    <meta charset="UTF-8">
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    <title>数组拍平</title>
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    <h3>编写一个 JavaScript 函数，接受一个仅包含数字的 多维数组 ，返回拍平以后的结果。</h3>
    <p>例如传入：[1, [[2], 3, 4], 5]，返回 [1, 2, 3, 4, 5]。</p>
    <script>
        const data = [1, [[2], 3, 4], 5];
        // 解法一
        const flatten = (arr) => {
            return arr.length ? arr.toString().split(',').map(Number) : []
        }
        // 解法二
        const flatten2 = (arr) => {
            let result = []
            arr.forEach(el => {
                if (typeof (el) === 'number') {
                    result.push(el);
                } else {
                    const item = flatten2.call(null, el);
                    result = result.concat(item)
                }
            })
            return result;
        }
        // 解法三
        const flatten3 = (arr) => {
            if (arr.length === 0) return [];
            const reg = /\[|\]/g;
            let str = JSON.stringify(arr);
            str = str.replace(reg, '')
            str = str.split(',').map(Number)
            return str;
        }
        console.log(flatten(data))
        console.log(flatten2(data))
        console.log(flatten3(data))
    </script>
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