Javascript Binary Tree

binary_tree.js

class Node {
  constructor(data) {
    this.data = data;
    this.left = null;
    this.right = null;
    this.inorderOut = [];
    this.preorderOut = [];
    this.postorderOut = [];
  }
  insert(data) {
    if(data < this.data) {
      if(this.left != null) {
        this.left.insert(data);
      } else {
        this.left = new Node(data);
      }
    } else {
      if(this.right != null) {
        this.right.insert(data);
      } else {
        this.right = new Node(data);
      }
    }
  }
  contains(item) {
    if(item === this.data) {
      return true;
    }
    
    if(item < this.data) {
      if(this.left != null) {
        return this.left.contains(item);
      } else {
        return false;
      }
    } else {
      if(this.right != null) {
        return this.right.contains(item);
      } else {
        return false;
      }
    }
  }
  inorder(out) {
    if(!out) {
      out=this.inorderOut;
    }
    if(this.left != null) {
      this.left.inorder(out);
    }
    out.push(this.data);
    if(this.right != null) {
      this.right.inorder(out);
    }
    return this.inorderOut;
  }
  preorder(out) {
    if(!out) {
      out=this.preorderOut;
    }
    out.push(this.data);
    if(this.left != null) {
      this.left.preorder(out);
    }
    if(this.right != null) {
      this.right.preorder(out);
    }
    return this.preorderOut;
  }
  postorder(out) {
    if(!out) {
      out=this.postorderOut;
    }
    if(this.left != null) {
      this.left.postorder(out);
    }
    if(this.right != null) {
      this.right.postorder(out);
    }
    out.push(this.data);
    return this.postorderOut;
  }
}