Tree Traversal for Binary Trees

We’ll start with this binary tree:

         11
        /  \
       7    15
      / \   / \
     2  8  13  18

Let’s express it in JavasScript as:

const binaryTreeB = {
  value: 11, 
  left: {
    value: 7, 
    left: {
      value: 2, 
      left: null, 
      right: null
    }, 
    right: {
      value: 8, 
      left: null, 
      right: null
    }
  }, 
  right: {
    value: 15,
    left: {
      value: 13, 
      left: null, 
      right: null
    }, 
    right: {
      value: 18, 
      left: null, 
      right: null
    }
  }
};

How could we write a function that traverses this tree, and logs each node to the console? Given what we’ve learned about binary trees, give it a shot with the following function.

function logBinaryTree(tree) {
	
}
logBinaryTree(binaryTreeB)

Give it a try before looking at the following solution.

function logBinaryTree(tree) {
  console.log(tree.value);
  if (!tree.left && !tree.right) return;
  if (tree.left && tree.right) {
    return logBinaryTree(tree.left) || logBinaryTree(tree.right)
  }
}
logBinaryTree(binaryTreeB)

Let’s write a function that logs a node to the console only if it’s an integer.

const binaryTreeC = {
  value: 11, 
  left: {
    value: "a", 
    left: {
      value: "c", 
      left: null, 
      right: null
    }, 
    right: {
      value: 8, 
      left: null, 
      right: null
    }
  }, 
  right: {
    value: false,
    left: {
      value: 13, 
      left: null, 
      right: null
    }, 
    right: {
      value: "b", 
      left: null, 
      right: null
    }
  }
};

Write a function onlyIntegersTree that only logs the integer values of a binary tree.

function onlyIntegersTree(tree) {

}
onlyIntegersTree(binaryTreeC);

Give it a try before looking at the following solution.

function onlyIntegersTree(tree) {
  if (Number.isInteger(tree.value)) console.log(tree.value);
  if (!tree.left && !tree.right) return;
  if (tree.left && tree.right) {
    return onlyIntegersTree(tree.left) || onlyIntegersTree(tree.right)
  }
}
onlyIntegersTree(binaryTreeC);