This assessment consists of functions you need to write involving manipulating arrays and objects. And maybe arrays of objects. It is a closed book assessment. You should stay on this tab until you are done and there should be no talking. This assessment is about how much you understand. There are no automatic tests but you can use the REPL to test things yourself.
Note: on this assessment you will be asked to write functions that call other functions you will write as part of the assessment. If you don’t know how to write one function you can still get full credit for a function that is supposed to call it as long as your code calls it appropriately, i.e. with correct syntax and passing the right arguments.
You can move through the questions with the arrows at the upper right next
to the 1 of indicator so if you're not
sure how to write one function move on to another one and come back if you
have time at the end. I want to see how much you do know. Note: you
can also click on thingsLikeThis in these instructions and
the questions to copy them to the clipboard to avoid spelling mistakes.
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When you are done, please click on your Github username above and
submit a GitHub pull request of the branch
and request me as a reviewer. Doing this correctly is part of the
assessment. If you are unsure how to request a review, please ask for
help!
Write a function named makeRow that takes no arguments
and returns a new three-element array where each element is the
empty string, ''.
Write a function named makeBoard that takes no
arguments and returns a 3x3 array. That is, it should return an
array containing three elements, each of which is a new array
containing three elements. The elements of the inner arrays should
all be the empty string, ''. In other words, the inner
arrays are rows such as are returned by the makeRow
function you just wrote, which you are free to use here if you want.
Write a function named makeMove that takes three
arguments: a string, specifying a mark (either 'X'
or 'O'); a number specifying a row; and a number
specifying a column. It should return an object with three
properties, mark, row,
and column, each with the value of the corresponding
argument.
Write a function named placeMark that takes a 3x3 array
like the ones returned by makeBoard and an object like
the ones returned by makeMove and sets the element of
the array at the row and column specified in the move object to the
move's mark.
The function does not need to return any specific value but after calling it the array passed as the first argument should be modified. For instance, after:
let board = makeBoard();
let move = makeMove('X', 1, 1);
placeMark(board, move);
the expression board[1][1] should evaluate to 'X'.
Write a function named allTheSame that takes an array
of three elements and returns true if all three
elements are === to each other and false
otherwise. For instance, allTheSame(['X', 'X', 'X'])
should return true.
Write a function named extractColumn that takes a 3x3
array like the ones returned by makeBoard and an index
from 0 to 2, inclusive, and returns a three-element array containing
the values in the column specified by the index, assuming the inner
arrays represent rows. For instance if board is the array:
[
['X', '', ''],
['O', '', ''],
['', 'X', '']
]
then extractColumn(board, 0) should return ['X', 'O',
'']
Write a function named recordMove that takes two
arguments: an array and a move object, like the ones returned
by makeMove. It should add the given move to the end of
the array.
The function does not need to return any specific value but after it is called the array argument should be one longer than it was before the call and the last element of the array should be the object passed as the second argument.
Write a function named rowForMove that takes two
arguments: an array of move objects like the ones collected
in recordMove and a number which is an index into that
array. It should return the row value (a number) of the move at the
given index.
For example after these two lines are executed:
let moves = [];
recordMove(moves, makeMove('X', 1, 2));
the call rowForMove(moves, 0) should return 1.
Write a function named placeMoves that takes two
arguments: a 3x3 array like the ones returned
by makeBoard and an array of moves such as might be
built up by repeatedly calling recordMove. The function
should call placeMark to place the mark for each move
in the array of moves in the correct position on the board array.
The function does not need to return any specific value though
obviously all the calls to placeMark will have updated
the board array argument. For instance after these lines are executed:
let moves = [];
let board = makeBoard();
recordMove(moves, makeMove('X', 1, 1));
recordMove(moves, makeMove('O', 0, 0));
recordMove(moves, makeMove('X', 0, 1));
placeMoves(board, moves);
then the board should be in this state: [['O',
'X', ''], ['', 'X', ''], ['', '', '']]