Traversal

Brute force looping:

for(let i=0; i<array.length; i++) {
  for(let j=0; j<array[i].length; j++) {
    console.log(array[i][j]);
  }
}

Length

const array = [
  [1,2,3],
  [4,5,6],
  [7,8,9],
];

let numRows = array.length;

let numCols = array[0].length;

Modifying

Adding a new row at the end:

const array = [
  [1,2,3],
  [4,5,6],
  [7,8,9],
];

// adding fourth row
array[3] = [10,11,12];

Removing a column:

const array = [
  [1,2,3],
  [4,5,6],
  [7,8,9],
];

// removing second column
for(let i=0; i<array.length; i++){
  // splice(start_at_index, el_count)
  array[i].splice(1,1); // remove 1 element (col) at index 1 of each row
}

// result
[1,3]
[4,6]
[7,9]

Remove a row:

const array = [
  [1,2,3],
  [4,5,6],
  [7,8,9],
];

// remove a second row
array.splice(1,1); // remove 1 element (row) at index 1

// result
[1,2,3]
[7,8,9]

Control Flow

break for exiting loop as whole.

• moves to outer scope/loop.

continue to skip current iteration.

• moves to i++ of current loop.