Question

I have an array that contains an array of arrays if that makes any sense. so for example:

[[1, 2, 3], [2, 3, 4], [3, 4, 5], [4, 5, 6]]

I want to see whether an array exists withing the array, so if [1, 2, 3] is duplicated at all. I have tried to use the .indexOf method but it does find the duplicate. I have also tried Extjs to loop through the array manually and to evaluate each inner array, this is how I did it:

var arrayToSearch = [[1, 2, 3], [2, 3, 4], [3, 4, 5], [4, 5, 6]];        
var newArray = [1, 2, 3];
Ext.each(arrayToSearch, function(entry, index){
                    console.log(newArray, entry);
                    if(newArray == entry){
                        console.log(index);
                    };
                });

This also does not detect the duplicate. the console.log will output [1, 2, 3] and [1, 2, 3] but will not recognize them as equal. I have also tried the === evaluator but obviously since == doesn’t work the === wont work. I am at wits end, any suggestions.

Answer 1

Comparing the two arrays using == or === will not work because they are not the same object. If you want to determine the element-wise equality of two arrays you need to compare the arrays element-wise.

I doubt you’ll gain anything from using tricks like join(',') and then using string operations. The following should work though:

function arraysAreEqual (a, b) {
  if (a.length != b.length) {
    return false;
  }

  for (var i=0; i<a.length; i++) {
    if (a[i] != b[i]) {
      return false;
    }
  }

  return true;
}

function containsArray (arrays, target) {
  for (var i=0; i<arrays.length; i++) {
    if (arraysAreEqual(arrays[i], target)) {
      return true;
    }
  }

  return false;
}

var arraysToSearch = [[1, 2, 3], [2, 3, 4], [3, 4, 5], [4, 5, 6]];
var newArray = [1, 2, 3];
containsArray(arraysToSearch, newArray);