Finding index of value in two dimensional array of objects in javascript

arrays, for-loop, javascript, multidimensional-array

Solution

Wrap your code in a function, replace your comment with `return i`, fallthrough by returning a sentinel value (e.g. -1):

function indexOfRowContainingId(id, matrix) {
  for (var i=0, len=matrix.length; i<len; i++) {
    for (var j=0, len2=matrix[i].length; j<len2; j++) {
      if (matrix[i][j].id === id) { return i; }
    }
  }
  return -1;
}
// ...
indexOfRowContainingId(222, arr); // => 1
indexOfRowContainingId('bogus', arr); // => -1

Problem

I have a 2D array of objects like so: ``` [[{id: 123}, {id: 456}, {id: 789}], [{id: 111}, {id: 222}, {id: 333}], [{id: 444}, {id: 555}, {id: 666}], [{id: 777}]] ``` I need to find the index of the id at the top array level. So if i was to search for and id property with value '222' i would expect to return an index of 1. I have tried the following: ``` var arr = [[{id: 123}, {id: 456}, {id: 789}], [{id: 111}, {id: 222}, {id: 333}], [{id: 444}, {id: 555}, {id: 666}], [{id: 777}]], len = arr.length ID = 789; for (var i = 0; i < len; i++){ for (var j = 0; j < arr[i].length; j++){ for (var key in o) { if (key === 'id') { if (o[key] == ID) { // get index value } } } } } ```

Original source