I'm trying to remove all the numbers from an array. The loop works exactly as I want, but the splice() method still skips some elements for some reason.

```
let arr = ['1', '2', '3', '4', '5', 'notanumber', '6'];

for (let element of arr) {
  let index = arr.indexOf(element);
  let check = isNaN(element);
  if (check === false) {
    arr.splice(index, 1);
  };
};

console.log(arr);

```

Expected output is: `['notanumber']`  

Current output is: `['2', '4', 'notanumber']`