126-128 = Support for the Firefox browser without polyfill (Firefox do not support event as global).

Proposition : 

```javascript
    //line 72-80
    if (this.filter == 'all') {
        return this.todos
      } else if (this.filter == 'active') {
        return this.todos.filter(todo => !todo.completed)
      } else if (this.filter == 'completed') {
        return this.todos.filter(todo => todo.completed)
      }
      
      return this.todos
```
You are returning the same thing with first if and last return the if do not make sense. 
This should look like that : 
```javascript
     if (this.filter == 'active') {
        return this.todos.filter(todo => !todo.completed)
      } else if (this.filter == 'completed') {
        return this.todos.filter(todo => todo.completed)
      }
      
      return this.todos
```
But personally, I'd use switch over if's, just like this :

```javascript
  switch (this.filter){
    case 'active':
      return this.todos.filter( todo => !todo.completed )
    case 'completed':
      return this.todos.filter( todo => todo.completed )
    }

    return this.todos //still not sure if this should have default return when all we know all cases
```
Cheers, 
Jakub