Quoting Ian’s answer:
Since the second parameter expects a function reference, you need to provide one. With your problematic code, you’re immediately calling the function and passing its result (which is
undefined
…because all the function does isalert
and doesn’t return anything). Either call the function in an anonymous function (like your first example) or alter the function to return a function.
function message_me(m_text){
alert(m_text)
}
second.addEventListener('click',
function() {
message_me('shazam');
}
);
Here’s an updated fiddle.