Reinitializing Variables Inside a Loop

JavaScript
1

Tell us what’s happening:
why this code only works when row is declared inside the outer loop

Your code so far


function zeroArray(m, n) {
  // Creates a 2-D array with m rows and n columns of zeroes
  let newArray = [];
  
  for (let i = 0; i < m; i++) {
    // Adds the m-th row into newArray
    let row = [];
    for (let j = 0; j < n; j++) {
      // Pushes n zeroes into the current row to create the columns
      row.push(0);
    }
    // Pushes the current row, which now has n zeroes in it, to the array
    newArray.push(row);
  }
  return newArray;
}

let matrix = zeroArray(3, 2);
console.log(matrix);

Your browser information:

User Agent is: Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/72.0.3626.121 Safari/537.36.

Link to the challenge:
https://learn.freecodecamp.org/javascript-algorithms-and-data-structures/debugging/use-caution-when-reinitializing-variables-inside-a-loop

2

Variable row is meant to be only subarrays, nested down only one level from newArray.

If row variable is outside of outer loop, then row array won’t get initialized again after “rows” end, but will only keep adding more items to itself.