Question

我使用下面的函数解决了来自FreeCodeCamp的算法挑战，但我想知道这是否是一个好的＆＃34;解决问题的方法，最具体地说，因为我将我的计数器设置为i + = 0并从头部拼接索引。我在这里创建了一个反模式吗？有什么更合乎逻辑的，你能解释一下原因吗？提前感谢您的帮助！

function chunk(arr, size) {
  var newArr = [];
  for (i=0; i<arr.length; i+=0) { 
      var sliced = arr.slice(i, size);
      newArr.push(sliced);
      arr.splice(0, size);
  }
  return newArr;
}
chunk([0, 1, 2, 3, 4, 5, 6, 7, 8], 4);
returns--> [ [ 0, 1, 2, 3 ], [ 4, 5, 6, 7 ], [ 8 ] ]

Answer 1

也许是递归？

function chunk(arr, size, out) {

  // if the output array hasn't been passed in
  // create it
  out = out || [];

  // if there are no elements in the input array
  // return the output array
  if (!arr.length) return out;

  // push the "head" of the input array to the
  // output array
  out.push(arr.slice(0, size));

  // call chunk again with the "tail" of the input array
  return chunk(arr.slice(size), size, out);
}

DEMO

Answer 2

我在这里创建了一个反模式吗？有什么更合乎逻辑的，你能解释一下原因吗？

您的代码包含一些可改进的部分

function chunk(arr, size) {
  //newWhatever, myWhatever, ... look for a better naming like `out` or `result` 
  //or in this case `chunks` would describe the content of the variable
  var newArr = [];

  //you initialize `i` without the var-keyword, therefore you populate/pollute the global namespace
  //and instead of calculating i+=0, you can leave this part empty:
  //for(var i=0; i<arr.length; ){
  for (i=0; i<arr.length; i+=0) { 
      var sliced = arr.slice(i, size);
      newArr.push(sliced);

      //splicing (with P) is often a thing that should be avoided, 
      //- it is destructive (it destroys the input-array)
      //- it is slow, cause the engine has to allocate new memory 
      //  and copy the remaining elements over to this memory,
      //  and garbage-collect the old memory
      arr.splice(0, size);
  }
  return newArr;
}

更好的解决方案是：

function chunk(arr, size) {
    for(var chunks=[], i=0; i<arr.length; i+=size)
        chunks.push(arr.slice(i, size));
    return chunks;
}

假设输入正确。

对于completenes，您应该添加一些输入验证。那个arr到位，可以切片，并且具有长度属性并且该大小是整数＆gt; 0否则代码可能会产生奇怪的结果。

function chunk(arr, size) {
    //checks if arr is not empty and arr.slice is not empty 
    //and casts the length-property to int
    //if anything "fails" len = 0;
    var len = (arr && arr.slice && arr.length)|0;

    //check if size is > 1 and is an integer
    if(size !== Math.floor(size) || size < 1)
        throw new Error("invalid chunl-size: "+size);

    for(var chunks=[], i=0; i<len; i+=size)
        chunks.push(arr.slice(i, size));
    return chunks;
}

Answer 3

function chunk(arr, size) {
    var subArrayCount = arr.length / size;
    var res = [];
    for (i = 0; i < subArrayCount; i++) {
        var from = size * i;
        var to = (size * (1 + i));
        console.log(to)
        var sliced = arr.slice(from, to);
        res.push(sliced);
    }
    return res;
}
chunk([0, 1, 2, 3, 4, 5, 6, 7, 8], 4);
returns--> [ [ 0, 1, 2, 3 ], [ 4, 5, 6, 7 ], [ 8 ] ]

将阵列拆分为二维阵列：有更好的解决方案吗？

3 个答案: