javascript - JS Recursive function call -

if call function once this

var button = document.queryselector('button');  button.addeventlistener('click', once);  function once() {   console.log('one');    button.removeeventlistener('click', once); } 

it's calling once.

but if called once()

var button = document.queryselector('button');  button.addeventlistener('click', once());  function once() {   console.log('one');    button.removeeventlistener('click', once()); } 

exception throws

exception: internalerror: recursion

could please explain why happening.

() after function name invoke's function. button.addeventlistener('click', once()); bind return value of once() method undefined.

and since once() called recursively without break statement, getting internalerror: recursion.

you should pass function reference.

button.addeventlistener('click', once);  

for additional info:

pointer vs delegates