Cannot read property 'apply' of undefined"

[l ll，修改在8 年前。]

Hello!

       var cell = A.all("#cels div");
	cell.hover(function(e) {
		this.setStyle('border', '5px solid #555');
    });

In the console, persistent errors : "Uncaught TypeError: Cannot read property 'apply' of undefined"
In what may be the reason?

[l ll，修改在8 年前。]

Noticed errors occur when leaving the cell cursor

[Julien Mourad，修改在8 年前。]

The hover method takes 2 parameters, one for mouse over and one for mouse out. Your code is missing the mouse out function hence the error.
http://alloyui.com/api/classes/A.Node.html#method_hover

cell.hover(function(){
    console.log("mouseover");
}, function(){
    console.log("mouseout");
});

[l ll，修改在8 年前。]

Thank you!

[David H Nebinger，修改在8 年前。]

Perhaps there was no match for "#cels div". Personally I'd wonder if maybe the "cels" was misspelled, but not sure.