How to access 2D array using single for loop in JavaScript?

Question

I have a 2D array which has 10 rows and 10 columns and I want to access a column's element from each row like this:

myArray[0][9]
myArray[1][4]
myArray[2][5]
myArray[3][9]
myArray[4][5]
myArray[5][9]
myArray[6][8]
myArray[7][9]
myArray[8][7]; 
myArray[9][8] 

The code that I have used:

for(var i=0; i<theatregoers.length; i++)
 {
 myArray[i][9].position=true;
 
 
 }

Note: I do not have any idea how to change column numbers like this each time when loop run. I do not want to use the nest loop, just using a single loop.

• tdranv: What is it that you are trying to achieve?
• user3718511: @tdranv thanks for ur response, actually I want to access column of each arrow according to the pattern that I mentioned above.
• Jerome: Could you elaborate on the pattern?
• user3718511: @Jerome myArray[0][9] myArray[1][4] myArray[2][5] myArray[3][9] myArray[4][5] myArray[5][9] myArray[6][8] myArray[7][9] myArray[8][7] myArray[9][8]
• Karl L: is there a particular pattern you want in calling the column number or it could be just random?

Answer 1

You can do something like this. put the column indexes/number in an array like:

 let colArray = [9,4,5,9,5,9,8,9,7,8] 
 
 for(var i=0; i<myArray.length; i++){ 
 myArray[i][colArray[i]].position=true; 
 }

Answer 2

You can loop your array like this

var row = 10;
var column = 10;
for (var i = 0; i < row * column; i++) {
 myArray[Math.floor(i / row)][i % column].position = true;
}

• Avius: The OP asked for an arbitrary pattern for the second index, so this answer is incorrect.
• catcon: @Avius: agree, OP added more info later in the comment