javascript - jQuery 3.x .off() after .on() -

i used .off() method after .on() method .click() method.
i'm confused why click() event fires!

$('span').on('click', function () { $('p').text("you clicked!") });    $('span').off('click', function () {     $('p').text("ha ha ha!") });

span{    background-color:#ac0;    padding:5px;    cursor:pointer;  }

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>  <span>click me!</span>  <p>*****</p>

you've misunderstood function @ end of off() method. isn't callback, it's event handler.

that function supposed same event handler function 1 set initially. done way can remove individual click handler.

function handlera(e) {   console.log('heard a'); }  function handlerb(e) {   console.log('heard b'); }  // add both handlers click events $('span').on('click', handlera); $('span').on('click', handlerb);  // remove first click event only, leaving second $('span').off('click', handlera); 

the above log heard b when clicked.

to remove all click handlers, need omit function entirely.

$('span').off('click');