数组扁平化

数组扁平化是指将一个多维数组变为一维数组

[1, 2, [3, 4, [5, 6], 7], 8, 9]    >   [1, 2, 3, 4, 5, 6, 7, 8, 9] 

方法

<script>
  
  let arr = [1, 2, [3, 4, [5, 6], 7], 8, 9]

  function fn1(data) {
    let arr1 = []
    if (Array.isArray(data)) {
      for (let index = 0; index < data.length; index++) {
        if (Array.isArray(data[index])) {
          arr1 = arr1.concat(fn1(data[index]))
        } else {
          console.log(data[index]);
          arr1.push(data[index])
        }
      }
    }
    return arr1
  }

  let arr2 = fn1(arr)
  console.log(3, ":", arr2);

</script>