This was a technical interview assignment. In the Eight Queens Puzzle you put eight queens on a chessboard, all in safe positions. It's usually solved with a recursive algorithm but I don't know recursive programming so I wrote a JavaScript program that places seven queens on the board, and another JavaScript program that places eight rooks on the board.
First I wrote 8_Rooks.js:
R - - - - - - -
- R - - - - - -
- - R - - - - -
- - - R - - - -
- - - - R - - -
- - - - - R - -
- - - - - - R -
- - - - - - - R
Then I added diagonals and got 5_Queens.js:
Q - - - - - - -
- - - Q - - - -
- Q - - - - - -
- - - - Q - - -
- - Q - - - - -
- - - - - - - -
- - - - - - - -
- - - - - - - -
By commenting out lines 326-332 I got 7_Queens.js:
Q - - - - - - -
- - - - Q - - -
- Q - - - - - -
- - - - - Q - -
- - Q - - - - -
- - - - - - Q -
- - - Q - - - -
- - - - - - - -
I wrote a blog post last year about writing nested loops by first writing out the code without loops, then abstracting one loop, and finally abstracting the 2nd loop. It's slow and tedious at first but saves time (and mental strain) debugging nested loops.
I started with 1_Rook.js, which uses a one-dimensional array to represent one row of the chessboard, and uses a for loop in a forEach loop to place one rook in the first square.
Next I wrote 8_Rooks_1stLoop.js with a two-dimensional array representing the entire chessboard, a forEach loop iterating through each row, and eight single for loops nested in the forEach loop,
each iterating through the squares of each row placing one rook correctly in each row.
Finally I abstracted the eight singles for loops into a single third-level (nested) for loop in 8_Rooks_2ndLoop.js. The third loop iterates through each square in a column.
8_Rooks.js(no loops) is 496 lines.8_Rooks_1stLoop.js(eight single loops nested in a forEach loop) is 91 lines.8_Rooks_2ndLoop.js(triple nested loops) is 26 lines.
As much as I enjoy programming challenges like this, in my experience JavaScript is more about connecting resources, e.g., getting Node's app.js to talk to the express.Router module while each route uses the Mongoose Node module to query the MongoDB database and then sends the data as a JSON object to the API so that the Angular front-end can receive the data, then setting up two-way data binding so that Angular can display
the data in the views, which are controlled by Angular's router, etc. Most projects have a dozen or more components. The challenges are choosing components that will work well together and getting them to talk to each other. Five months after graduation my classmates are still slacking each other asking which components work best with other components.
For my Galvanize capstone project I hooked up WebRTC video conferencing with a cloud database (Firebase) to give Angular five-way data binding (two users each with two-way data binding connected via AngularFire cloud data binding). You can go to the website, see a list of players waiting for a game, click a name and open a video conference window, then play a tic-tac-toe game with the other user. The code isn't pretty and it's just a tic-tac-toe game but our Director of Instruction told me that his jaw dropped when I demo'd it at our Hiring Day.
To make an analogy, in the years that I was an electronics engineer I used little of the math I learned in college, and instead studied telephone-book sized catalogs from distributors to see what parts were available, then figured out how to put the pieces together.
If you're looking for a coder who can recursively write triple nested loops to iterate over two-dimensional arrays, last summer I AirBnB hosted two wonderfully nice MIT students interning at Google. If you need someone to figure out how to hook up stuff no one has ever put together to make apps that solve customers' problems, that's what Galvanize graduates do.