`bind` method wrap current function by another anonymous function.
See the following example:
```javascript
a = function () {}
b = a.bind(window)
a==b // => false
c = a
a==c // => true
```
So:
```javascript
$(window).off('click', _clickHandler);
```
will not remove handler that is bound so:
```javascript
$(window).on('click', _clickHandler.bind(state));
```
Because
```javascript
_clickHandler.bind(state) != _clickHandler
```