javascript - How to prevent default on form submit? -

if can prevent default on form submit fine:

document.getelementbyid('my-form').onsubmit(function(e) {    e.preventdefault();    // }); 

but since organizing code in modular way handling events this:

document.getelementbyid('my-form').addeventlistener('onsubmit', my_func);  var my_func = function() {    // how prevent default here???    // } 

how can prevent default now?

the same way, actually! demo

some html

<form id="panda" method="post">     <input type="submit" value="the panda says..."/> </form> 

your javascript

// function var my_func = function(event) {     alert("me , relatives owned china");     event.preventdefault(); };  // form var form = document.getelementbyid("panda");  // attach event listener form.addeventlistener("submit", my_func, true); 

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note: when using .addeventlistener should use submit not onsubmit.

note 2: because of way you're defining my_func, it's important call addeventlistener after define function. javascript uses hoisting need careful of order of things when using var define functions.

read more addeventlistener , eventlistener interface.