Using a for loop to populate a two-dimensional array in JavaScript

Currently, I'm attempting to populate a two-dimensional array in JavaScript using the following method:

var i = 0, j = 0;
for (i = 0; i < roomWidth / tileWidth; i += 1) {
     roomBuffer[i] = [];
}
for (i = 0; roomWidth / tileWidth; i += 1) {
     for (j = 0; j < roomHeight / tileHeight; j += 1) {
          roomBuffer[i][j] = 1;
     }
}
alert("Hello world");

The issue I'm encountering is that not only does this code fail to execute properly, but it also prevents any subsequent code from running. For example, the alert("Hello world"); does not appear. Could someone please advise on where I may be going wrong?

javascriptarraysfor-loop

Answer №1

update

for (i = 0; roomWidth / tileWidth; i += 1) {

to

for (i = 0; i < roomWidth / tileWidth; i += 1) {

Answer №2

Declaring i and j before the loops is unnecessary. If they are only needed within the loops, it's better to define them as local variables. Additionally, you can optimize by combining loops.

I agree with @Yuriy Zubarev's point that the middle statement in the for-loop must remain true throughout the entire loop execution.

for (var i = 0; i < roomWidth / tileWidth; i++) {
     roomBuffer[i] = [];
     for (var j = 0; j < roomHeight / tileHeight; j++) {
          roomBuffer[i][j] = 1;
     }
}
alert("Greetings universe");

Answer №3

Take a look at this code snippet.

Update your

for (i = 0; roomWidth / tileWidth; i += 1)

to

for (i = 0; i < roomWidth / tileWidth; i += 1)

Answer №4

If you want to streamline your code, consider incorporating a compact helper function

// generate an array of specified length filled with a specific value
populateArray = function(length, val) {
    for (var arr = []; length-- > 0; arr.push(val));
    return arr;
}

Your current code snippet:

numTiles = roomWidth / tileWidth
roomLayout = populateArray(numTiles, populateArray(numTiles, 1))

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