postOrder() {

        let result = [];

​

        let recursive = (node) => {

            if (node.left) {

                recursive(node.left);

            }

            if (node.right) {

                recursive(node.right);

            }

            result.push(node.value);

        }

​

        recursive(this.root);

​

        return result;

    }

​

}

//if you find the answer is useful ,

//upvote for it, so can the others benefit also ༼ つ ◕_◕ ༽つ 

 preOrder() {

        let result = [];

​

        let recursive = (node) => {

            result.push(node.value);

            if (node.left) {

                recursive(node.left);

            }

​

            if (node.right) {

                recursive(node.right);

            }

        }

​

        recursive(this.root);

​

        return result;

    }

//if you find the answer is useful ,

//upvote for it, so can the others benefit also ༼ つ ◕_◕ ༽つ @mohammad alshraideh ( ͡~ ͜ʖ ͡°)⇑⇑

inOrder() {

        let result = [];

​

        let recursive = (node) => {

            if (node.left) {

                recursive(node.left);

            }

            result.push(node.value);

​

            if (node.right) {

                recursive(node.right);

            }

        }

​

        recursive(this.root);

​

        return result;

    }

//if you find the answer is useful ,

//upvote for it, so can the others benefit also ༼ つ ◕_◕ ༽つ @mohammad alshraideh ( ͡~ ͜ʖ ͡°)⇑⇑