# Javascript: Binary tree aggregation

JS: Introduction to Object Oriented Programming (OOP)Last update: 14 Jan 23:20

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Students

In this test, we will use a binary tree, and perform data aggregation.

## Node.js

Implement the following class methods:

`getCount()`

returns the number of nodes in the tree`getSum()`

returns the sum of all tree keys`toArray()`

returns a one-dimensional array containing all keys`toString()`

returns a string representation of the tree`every(fn)`

verifies that all tree keys meet the criteria stated in the passed function`some(fn)`

verifies that at least one tree key meet the criteria stated in the passed function

Use the left-to-right order when traversing the tree. That is, first we process the node key, then the left child key, then the right child key.

### Examples

```
const tree = new Node(9,
new Node(4,
new Node(8),
new Node(6,
new Node(3),
new Node(7))),
new Node(17,
null,
new Node(22,
null,
new Node(20))));
tree.getCount() // 9
tree.getSum(); // 96
tree.toArray(); // [9, 4, 8, 6, 3, 7, 17, 22, 20]
tree.toString(); // '(9, 4, 8, 6, 3, 7, 17, 22, 20)'
tree.every((key) => key <= 22); // true
tree.every((key) => key < 22); // false
tree.some((key) => key < 4); // true
tree.some((key) => key > 22); // false
```

### Tips

- Binary tree
- To implement each of the methods, you will need to traverse all the tree nodes
- Recall the reduce array method

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