check if array of arrays is sorted javascript

Question

I need to see if this type of array is sorted:

var grilla = [
    [1, 2, 3],
    [4, 5, 6],
    [7, 8, 9]
];

I know how to show all of the elements and how to see if a simple array is sorted, but no clue on how to do this. My "solution" doesn't cover cases like [ [1, 2, 3], [4, 5, 6], [8, 7, 9] ] where the complete array of arrays is unsorted because of the last array, but I don't know how to reach the last array to check if it's sorted.

function chequearSiGano() {
    for(var i=0;i<(grilla.length-1);i++) {
      if (grilla[i][grilla.length-1] > grilla[i+1][0]) {
        return false;
      }
      for(var j=0;j<(grilla.length-1);j++) {
        if (grilla[i][j] > grilla[i][j+1]) {
          return false;
        }
      }
    }
    return true;
}

Answer 1

To make it easy, flatten the array

Then you can either use the code you use for a flat array or you can even go like the following

const checkIfSorted = array => {
  var flat = array.flat();
  var flatsorted = flat.slice().sort();
  return flat.toString() === flatsorted.toString();
}

var grill = [
  [1, 2, 3],
  [4, 5, 6],
  [7, 8, 9]
];
console.log('grill sorted?', checkIfSorted(grill))
var grill2 = [
  [1, 2, 4],
  [3, 5, 6],
  [7, 8, 9]
];
console.log('grill2 sorted?', checkIfSorted(grill2))

Answer 2

You can use .flat() function that converts nested array into flat array and check it as simple array: e.g.:

const grill = [
    [1, 2, 3],
    [4, 5, 6],
    [7, 8, 9]
 ];
const flattedArray = grill.flat()
function chequearSiGano() {
    for(let i=0;i<(flattedArray .length-1);i++) {
      if (flattedArray[i] > flattedArray[i+1]) {
        return false;
      }
    }
    return true;
}