```coffeescript
do ($$ = Quo) ->

    VENDORS = [ "-webkit-", "-moz-", "-ms-", "-o-", "" ]

    $$.fn.addClass = (name) ->
        @each ->
            unless _existsClass(name, @className)
                @className += " " + name
                @className = @className.trim()

    $$.fn.removeClass = (name) ->
        @each ->
            unless name
                @className = ""
            else
                @className = @className.replace(name, " ").replace(/\s+/g, " ").trim() if _existsClass(name, @className)

    $$.fn.toggleClass = (name) ->
        @each ->
            if _existsClass(name, @className)
                @className = @className.replace(name, " ")
            else
                @className += " " + name
                @className = @className.trim()

    $$.fn.hasClass = (name) ->
        _existsClass name, this[0].className

    $$.fn.style = (property, value) ->
        if value
            @each -> @style[property] = value
        else
            this[0].style[property] or _computedStyle(this[0], property)

    $$.fn.css = (property, value) -> @style property, value

    $$.fn.vendor = (property, value) ->
        @style("#{vendor}#{property}", value) for vendor in VENDORS

    _existsClass = (name, className) ->
        classes = className.split(/\s+/g)
        classes.indexOf(name) >= 0

    _computedStyle = (element, property) ->
        document.defaultView.getComputedStyle(element, "")[property]
```

Fix for when the array is empty
user
```coffeescript
do ($$ = Quo) ->

    VENDORS = [ "-webkit-", "-moz-", "-ms-", "-o-", "" ]

    $$.fn.addClass = (name) ->
        @each ->
            unless _existsClass(name, @className)
                @className += " " + name
                @className = @className.trim()

    $$.fn.removeClass = (name) ->
        @each ->
            unless name
                @className = ""
            else
                @className = @className.replace(name, " ").replace(/\s+/g, " ").trim() if _existsClass(name, @className)

    $$.fn.toggleClass = (name) ->
        @each ->
            if _existsClass(name, @className)
                @className = @className.replace(name, " ")
            else
                @className += " " + name
                @className = @className.trim()

    $$.fn.hasClass = (name) ->
        this.length > 0 and _existsClass name, this[0].className

    $$.fn.style = (property, value) ->
        if value
            @each -> @style[property] = value
        else if this.length > 0
            this[0].style[property] or _computedStyle(this[0], property)

    $$.fn.css = (property, value) -> @style property, value

    $$.fn.vendor = (property, value) ->
        @style("#{vendor}#{property}", value) for vendor in VENDORS

    _existsClass = (name, className) ->
        classes = className.split(/\s+/g)
        classes.indexOf(name) >= 0

    _computedStyle = (element, property) ->
        document.defaultView.getComputedStyle(element, "")[property]
```
assistant