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Vanessa Zavarse
Courses Plus Student 1,778 PointschangeColor() or changeColor? I do not understand why the change event method receives changeColor and not changeColor()
When we are adding the change method to input why it receives as arguments changeColor not changeColor () with parentheses?.
I have understood that if you want to call a function, you must also place this changeColor parentis () and not changeColor.
2 Answers
Bryan Knight
34,215 PointsVanessa,
This threw me off in the beginning as well. The reason you don't need the parens is because you want the function to be called upon a change. If you put the parens, it tells the javascript interpreter to call that functions immediately and then the result of that function (aka the return value) would be the actual parameter passed to the .change method.
So in other words you don't want to run the function until there is a change.
The jQuery function will handle the "calling" portion if that makes sense.
Jeremiah Lugtu
9,910 PointsBecause
function changeColor(){...};
can be written as:
var changeColor = function(){...};
read more here: https://javascriptweblog.wordpress.com/2010/07/06/function-declarations-vs-function-expressions/
Calvin Miracle
22,028 PointsCalvin Miracle
22,028 PointsHi Vanessa,
I see what you mean, along about the 6 minute mark..
This is an example of passing a function "handle" or function "reference" to another routine.
Andrew is not really "calling" the function at that point.. If he was, you'd be right about him having to use the parens.
What he's doing is "injecting" the changeColor function into the jQuery routine. jQuery will remember this handle and use it when it needs a way to actually change the color. The changeColor routine is called elsewhere, not at the point Andrew mentions it.
Indirection like that can be hard to follow, even for experienced programmers. But it lets you say things like "Hey jQuery routine! If you want to change color, use this capacity to change color that I just gave to you!" Passing a reference to something is like passing a capability.
Take care, good luck! -- Cal