Assigning event handler

Question

Assigning event handler like so:

document.addEventListener("DOMContentLoaded", myFunction);

is it required for the handler function to be defined before the assignment code? In other words if the codes below

function myFunction() {...}
...
document.addEventListener("DOMContentLoaded", myFunction);

and

document.addEventListener("DOMContentLoaded", myFunction);
...
function myFunction() {...}

are identical?

well.. did you try it for yourself...? What did you find...? — Sudhir Bastakoti, Sep 18 '17 at 10:10
@SudhirBastakoti: Trying it can be useful, but only tells you whether it works on the JavaScript engine(s) where you tried it, as opposed to whether it's *supposed* to work. — T.J. Crowder, Sep 18 '17 at 10:10
`function declaration` is hoisted which means it is evaluated before any other code in current context.. — Rayon, Sep 18 '17 at 10:11

score 2 · Accepted Answer · answered Sep 18 '17 at 10:10

...are identical?

They are if you use the form you've shown, which is a function declaration. Function declarations are processed before any step-by-step code in the scope. If you used a function expression instead (var myFunction = function() { ... };), it would have to be before the addEventListener call. More about the difference in this question's answers.

Assigning event handler

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