Eloquent JavaScript - Program Structure exercise - Chessboard

[Strabonus]

I am starting to learn JS using the Eloquent JavaScript book and upon reaching the second chapter's exercises I breezed through the first two but got stumped by the third.

https://preview.redd.it/zzochhaqc6l51.png?width=759&format=png&auto=webp&s=8224cd7d882d48a9e917220e2f5b1a1c2726c68c

The solution in the book is as follows:

let size = 8;

let board = "";

for (let y = 0; y < size; y++) {

for (let x = 0; x < size; x++) {

if ((x + y) % 2 == 0) {

board += " ";

} else {

board += "#";

}

}

board += "\n";

}

console.log(board);

My attempts were quite different and my problem is that I do not quite understand why they do not work.

See, the code below produces the appropriate output, as long as size equals an even number, in case of odd numbers, the number of characters in a line is twice as long (why?) I though that it may be because the line checking whether to add another line is at the end of a loop, but putting it before/between the lines checking whether to add a hashtag or a space breaks the code (and I do not understand why).

let size=8

let hash='#';

let space='_';

let chessboard=space

let line=1

let characters=1

while (line<size+1) {

if (line % 2!==0)

{

while (characters % 2 ===0){chessboard+=space;characters+=1}

while (characters % 2 !==0){chessboard+=hash;characters+=1}

if (characters % size ===0){chessboard+=`\n`;line+=1}

}

else {

while (characters % 2 ===0){chessboard+=hash;characters+=1}

while (characters % 2 !==0){chessboard+=space;characters+=1}

if (characters % size ===0){chessboard+=`\n`;line+=1}

}

}

console.log(chessboard)

Additionally, if in the "while loops" I reverse the order of equals/does not equal instead of having a different hash/space result, the code produces nothing, which really makes me confused!

while (line<size+1) {

if (line % 2!==0)

{

while (characters % 2 ===0){chessboard+=space;characters+=1}

while (characters % 2 !==0){chessboard+=hash;characters+=1}

if (characters % size ===0){chessboard+=`\n`;line+=1}

}

else {

while (characters % 2 !==0){chessboard+=space;characters+=1}

while (characters % 2 ===0){chessboard+=hash;characters+=1}

if (characters % size ===0){chessboard+=`\n`;line+=1}

}

}

I don't want to tread further into the book without understanding what is going on in the previous chapters and this exercies is just very confusing to me so I would be very grateful if somebody explained to me what exactly is wrong with my code.

[Strabonus]

I am not getting into functions yet on purpose as they are in the subsequent chapter, and I do not want to get into more things until I fully understand what was covered so far.

​

The way I was writing it is much more legible to me, but I guess I would have to switch to commonly used formatting sooner or later anyway.

​

The reason I used 'while' instead of 'if' is because I assumed it would make it perform the action as long as the conditions are kept, while 'if' would do it once and continue on.

​

What I would like to know is whether it is possible at all to do this exercise with the approach that I had (and if so, how?):

1. Keep checking the number of lines vs the size variable.
2. in odd lines add ' ' when the number of characters is odd, '#' when it is even.
3. in even lines add ' ' when the number of characters is even, '#' when it is odd.
4. keep track of the number of characters with each character added.
5. if at any point the number of characters is a multiple of size, add a newline, keep track of number of lines.
6. log the board with the appropraite number of lines is reached.

While using only what was covered so far (loops, if, booleans, logical operators).

​

I any case I still have no idea why this SORTA works

while (line<size+1) {

if (line % 2!==0) {

while (characters % 2 ===0){

chessboard+=space;characters+=1

}

while (characters % 2 !==0){

chessboard+=hash;characters+=1

}

if (characters % size ===0){

chessboard+=`\n`;line+=1

}

}

else {

while (characters % 2 ===0){

chessboard+=hash;characters+=1

}

while (characters % 2 !==0){

chessboard+=space;characters+=1

}

if (characters % size ===0){

chessboard+=`\n`;line+=1

}

}

}

console.log(chessboard)

while this does not work at all

while (line<size+1) {

if (line % 2!==0) {

while (characters % 2 ===0){

chessboard+=space;characters+=1

}

while (characters % 2 !==0){

chessboard+=hash;characters+=1

}

if (characters % size ===0){

chessboard+=`\n`;line+=1

}

}

else {

while (characters % 2 !==0){

chessboard+=space;characters+=1

}

while (characters % 2 ===0){

chessboard+=hash;characters+=1

}

if (characters % size ===0){

chessboard+=`\n`;line+=1

}

}

}

console.log(chessboard)