Question

I can’t seem to get back on track with this one. I simply put a function in a variable and want to call it later, providing it with a parameter:

var logic = function(itemId) {               
    console.log(itemId);
};

jQuery("#flipright").click(function() {  logic.apply(1); } );

This prints “undefinded”.

What am I missing?

Answer 1

Simply call logic(1).
If you want to pass a context, you can use call or apply :

logic.apply(context, [1]);
// or
logic.call(context, 1);

You should use apply or call if you want to pass a context to another function – meaning that the this keyword in the called function will refer to whatever context you are passing to it.
Here’s a scenario :

var logic = function(itemId) {               
    console.log(this,itemId);
};

jQuery("#flipright").click(function() {  
    // output to console the current jquery object and "1"
    logic.call(this,1);
});