Depth First Search

app.js

traverseDFS(type) {
		//if there is no root, return false
		if (!this.root) {
			return false;
    }
    //make a variable for tree values
    const treeValues = [];
    //current values always starts at root
    let current = this.root;
        
    //helper methods for order choice
		const preOrderHelper = node => {
			//push value onto array FIRST
			treeValues.push(node.value);
			//recursively call function on all node children
			if (node.children.length !== 0) {
				node.children.forEach(child => {
					preOrderHelper(child);
				});
			}
			return true;
		};

		const postOrderHelper = node => {
      //recursively call function on all node children FIRST
			if (node.children.length !== 0) {
				node.children.forEach(child => {
					postOrderHelper(child);
				});
      }
      //push value onto array
			treeValues.push(node.value);
			return true;
		};

		const inOrderHelper = node => {
      //if node has children, split nodes into left and right halves in case tree is not binary FIRST
				if (node.children.length !== 0) {
				  //get halfway point
					const halfway = Math.floor(node.children.length / 2);
					//recursively call function on all node children left of halfway point
					for (let i = 0; i < halfway; i++) {
						inOrderHelper(node.children[i]);
          }
          // push parent node value to array
          treeValues.push(node.value);
          //recursively call function on all node children right of halfway point
				  for (let i = halfway; i < node.children.length; i++) {
          	inOrderHelper(node.children[i]);
          }
          // else push value into array
			  } else {
				  treeValues.push(node.value);
			  }
			return true;
		};
	
    //switch statment to select proper order and start recursive function calls
		switch (type) {
			case "pre":
				preOrderHelper(current);
				break;
			case "post":
				postOrderHelper(current);
				break;
			case "in":
				inOrderHelper(current);
				break;
    }
        //return array
		return treeValues;
}