Help with Seek and Destroy...I think (I hope) I'm close [Solved]

Help with Seek and Destroy...I think (I hope) I'm close [Solved]
0

#1

My output is [2, 3, 2, 3] when it should be [1, 1] so I think I am filtering for the matching arguments rather than filtering them out. So basically I don’t understand filter, or indexOf. Or both. :confused:

function destroyer(arr) {
  var convertedArr = Array.prototype.slice.call(arguments);
  var targetArr = convertedArr[0];
  var filtered;
  function seeker(convertedArr) {  
    return targetArr.indexOf(convertedArr);
  }
  return filtered = targetArr.filter(seeker);
}

destroyer([1, 2, 3, 1, 2, 3], 2, 3);


#3

filter will remove values with a “falsy” return value from the fiter function and keep values with a “truthy” return value from the filter function.

indexOf will return the index of the value if found (including 0 which is falsy) and -1 if it is not found (-1 is truthy).

If you want to test whether an item is present in an array using indexOf:

arrayName.indexOf(something) !== -1 // true if something is in arrayName

#4

Thank you for your help, I finally did it. I have to say that this has been extremely frustrating. Either I am not very good at this kind of thing, or some of these algorithms are exceptionally hard for what they have taught up to this point. Either way, once I got it I felt like crying. So, there is that.

~ Brian

PS, here is my code :


SPOILER ALERT!

function destroyer(arr) {
  var convertedArr = Array.prototype.slice.call(arguments);
  var targetArr = convertedArr[0];
  convertedArr.shift(); 
  
  return targetArr.filter(function(i) {
    return convertedArr.indexOf(i) == -1;
  });  
}

destroyer([53, "hamburger", "tree"], "tree", 53);

#5

Go easy on yourself. It’s new. It’s hard. Some progressions will be more intuitive than others and sometimes you’ve hit a point where it’s time to make a jump to the next level of complexity.


#6

Thank you for the encouragement. The next two algorithms went pretty well and I feel a little boost of pride and confidence.