如何通过javascript从php访问添加的元素

Question

I am working on a small project and it is my first so, I have some difficulties to get over. I am creating a dynamic list for a filtered search and the problem is that I try to add elements with php and I want them to change visibility onclick and for that I use a css code which is fully functional but the problem is with the javascript which tells me:

script.js:4 Uncaught TypeError: Cannot read property 'classList' of null at visibilityToggle (script.js:4) at HTMLDivElement.onclick (afficherDept.php:4)

js_Code:

function visibilityToggle(id) {
    var section = document.getElementById(id);
    section.classList().toggle("showen");
}

and this is the php code for adding elements: ---$sectionID is controlled by a loop

echo '<div onclick="visibilityToggle('.$sectionID.');"id='.$id.'>'.'ID 
     '.$dept["id"].'. NOM:'. $dept["nom"].'.CHEF:'.$dept["chef"].'</div>';

echo '<section class="hidden" id=' . $sectionID . '>';

result in HTML

Answer 1

It makes no sense to call a function with onclick from an element, and then use document.getElementById to search for the same element again...

Instead I would add a class to your divs in PHP, and use javascript to add a click handler. This way you know who called the handler and you can toggle the CSS class directly. (note: haven't tested this but I hope the idea is clear)

PHP

echo '<div class="clickablediv">simple example</div>';

JAVASCRIPT

let clickableDivs = document.getElementsByClassname("clickablediv")
for(let d of clickableDivs){
    d.addEventListener("click", visibilityToggle)
}
function visibilityToggle(e) {
    e.target.classList().toggle("showen");
}

Answer 2

The cause for the denoted error is the wrongful rendering of the html markup from your php code.

You need to put quotes around the argument passed to the visibilityToggle function.

'<div onclick="visibilityToggle(\''. $sectionID. '\')"'

Next, the classList is a DOMTokenList object - not a function.

So, you should access the toggle property like this:

section.classList.toggle("showen");

Answer 3

thanks for all your answers. I fixed the problem. In my js function visibilityToggle, the argument id was a html element not a string. i don't know why but it worke