我正在尝试对二叉搜索树中的数组输入执行运行回调函数。我一直被告知我的回调函数 "is not a function"

Question

这是我创建二叉搜索树的代码以及添加到树中的原型方法。还有 preorder 方法以及一些调用来执行函数来测试它们...

function BinarySearchTree(value) {
    this.value = value;
    this.right = null;
    this.left = null;
  }
  
  BinarySearchTree.prototype.add = function(value) {
    if (value < this.value && this.left) {
      this.left.add(value);
    } else if (value < this.value) {
      this.left = new BinarySearchTree(value);
    }
  
    if (value > this.value && this.right) {
      this.right.add(value);
    } else if (value > this.value) {
      this.right = new BinarySearchTree(value);
    }
  
  };

 BinarySearchTree.prototype.depthFirstPre = function(callback) {
    callback(this.value);
    this.depthFirstPre(this.left);
    this.depthFirstPre(this.right);
  };

binarySearchTree = new BinarySearchTree(5);
var array = [];
var func = function(value){ array.push(value); };
binarySearchTree.add(2);
binarySearchTree.add(3);
binarySearchTree.add(7);
binarySearchTree.add(6);
binarySearchTree.depthFirstPre(func);
console.log(array) -> *should output [ 5, 2, 3, 7, 6 ]*

当我尝试执行 depthFirstPre 函数时，我总是收到“回调不是函数”的提示，我很困惑为什么。

感谢您的帮助，我们将不胜感激！

Answer 1

您可以添加一张支票并使用 this.left 或 this.right 进行通话。

function BinarySearchTree(value) {
    this.value = value;
    this.right = null;
    this.left = null;
}

BinarySearchTree.prototype.add = function(value) {
    if (value < this.value) {
        if (this.left) this.left.add(value);
        else this.left = new BinarySearchTree(value);
    }

    if (value > this.value) {
        if (this.right) this.right.add(value);
        else this.right = new BinarySearchTree(value);
    }
};

BinarySearchTree.prototype.depthFirstPre = function(callback) {
    callback(this.value);
    if (this.left) this.left.depthFirstPre(callback);
    if (this.right) this.right.depthFirstPre(callback);
};

BinarySearchTree.prototype.depthFirst = function() {
    return [
        this.value,
        ...(this.left ? this.left.depthFirst() : []),
        ...(this.right ? this.right.depthFirst() : [])
    ];
};

var binarySearchTree = new BinarySearchTree(5),
    array = [],
    func = function(value) { array.push(value); };

binarySearchTree.add(2);
binarySearchTree.add(3);
binarySearchTree.add(7);
binarySearchTree.add(6);
binarySearchTree.depthFirstPre(func);

console.log(...array); // [ 5, 2, 3, 7, 6 ]

console.log(...binarySearchTree.depthFirst());

我正在尝试对二叉搜索树中的数组输入执行运行回调函数。我一直被告知我的回调函数 "is not a function"

I am trying to do a run a callback function on an array input into a binary search tree.. I keep getting told my callback function "is not a function"

javascript

callback

binary-search-tree

preorder

我正在尝试对二叉搜索树中的数组输入执行 运行 回调函数。我一直被告知我的回调函数 "is not a function"

I am trying to do a run a callback function on an array input into a binary search tree.. I keep getting told my callback function "is not a function"

javascript

callback

binary-search-tree

preorder

我正在尝试对二叉搜索树中的数组输入执行运行回调函数。我一直被告知我的回调函数 "is not a function"