Iterative Tree Traversal

tree.ts

class Tree {
    value: Number;
    left: Tree | null;
    right: Tree | null;

    constructor(value: Number) {
        this.value = value;
        this.left = null;
        this.right = null;
    }

    insert(value: Number) {
        let node = this;
        if (node == null) {
            this.value = value;
            return;
        } else if (node.value == value) {
            return;
        } else if (value < node.value) {
            if (this.left) {
                this.left.insert(value);
            } else {
                this.left = new Tree(value);
            }
            return;
        } else {
            if (this.right) {
                this.right.insert(value);
            } else {
                this.right = new Tree(value);
            }
            return;
        }
    }

    inOrderPrintRecursive() {
        if (this == null) {
            return;
        } else if (this.left) {
            this.left.inOrderPrintRecursive();
        }
        if (this.value != undefined) {
            console.log(this.value);
        }
        if (this.right) {
            this.right.inOrderPrintRecursive();
        }
        return;
    }

    inOrderPrint() {
        var current: Tree = this;
        var ancestors = new Array();
        var notStarted = true;
        while (notStarted || ancestors.length > 0) {
            notStarted = false;
            while (current) {
                ancestors.push(current);
                current = current.left;
            }
            current = ancestors.pop();
            console.log(current.value);
            while (current) {
                current = current.right
                ancestors.push(current);
            }
            current = ancestors.pop();
        }
        return;
    }
}

Here it breaks down a bit! This loop isn't quite right... you're going to shoot very "right-wise" and skip some left "chains" you would've wanted to follow, happy to construct a problem-tree if you like