I want to change only the first column in the firs row but it doesn't work.
wanted output is [[1,0],[0,0]], but what I get is[[1,0],[1,0]]
I want to know why this happens and what is the solution if I want to make a change in a different index ?
let matrix = []; let row = [0, 0]; for (i = 0; i < 2; i++) { matrix.push(row); } matrix[0][0] = 1; console.log(matrix); The problem is, that you are pushing the same object (row) into the matrix twice. Make a copy of row for example with the spread operator, or Array.slice():
let matrix = []; let row = [0, 0]; for (i = 0; i < 2; i++) { matrix.push([...row]); } matrix[0][0] = 1; console.log(matrix);The variable row which is pushed to the matrix array points to the same memory location. So any update on this variable will be reflected everywhere. You need to create a new one every time you push it
let matrix = []; for (let i = 0; i < 2; i++) { let row = [0, 0]; matrix.push(row); } matrix[0][0] = 1; console.log(matrix);Either just push a new array:
matrix.push([0,0]) Or you can use the spread operator:
matrix.push([...row])
matrix.push(row);This is adding the same object over and over. When you change it in 1 place you change it in all the places.matrix.push([...row]);