Javascript cannot target DOM elements from inside this PHP code - javascript

Turning the header red isn't what I'm trying to achieve, I was actually trying to run a jQuery code, but this is just to show that (maybe) targeting DOM elements is the problem because a simple alert() works.
Also, the Javascript code that isn't working here does work outside this if statement.
if(!empty($_POST['description'])) {
$query = $con->prepare('insert into tasks (user_id, description) values (?,?)');
$query->execute(array($_SESSION['user_id'], $_POST['description']));
?>
<script>
alert('hi'); //works
document.querySelector('header').style.color = 'red'; //doesn't work
</script>
<?php
}

Your JavaScript code is maybe executed before your header is rendered, be sure to launch this code after your footer.
You may also have more than one header element in your page and your querySelector targets the wrong.

If your script executes prior to the header element being in the DOM, the querySelector will not be able to find it because it does not exist.
Try this to have the script exectute after the entire DOM has been parsed (e.g. everything between <html> ... </html>):
document.addEventListener("DOMContentLoaded", function(){
document.querySelector('header').style.color = 'red';
});

Related

javascript wont find the id/class of html/javascript imported code with XMLHttpRequest

i´m building a search system for this petshop software web base, the thing is that i search for a name, than send the name with XMLHttpRequest to php page that execute the query and return me the results and display them at my search page,until here is ok. the information that php page returns to search page goes like this:
<?php
$query = "selec ...
$queryName = mysqli_query...
while($fetchNames = mysqli_fetch_array...
?>
<a class="profile">
<div id="clientInfo"><?php echo $fetchNames[0]; ?></div>
</a>
<?php }
?>`
i try to acess the html class .profile imported on searchpage.php:
`<script>
document.querySelector('.profile').addEventListener('click',function=(){
alert('js code works!');
});
</script>
</body>`
i tryed to import it with the results of php query page right after the end of while loop, even with the window.onload=func... it won't work!
javascript won't work at the imported document, it can't see the class to display the alert. how can i work around this issue?
thanks in advance!
As you have dynamically-generated elements, you'll need to make use of event delegation and target an element that exists on page load, and work down from there. You haven't mentioned any parent elements in your question, so I'll target <body> in my answer, as this always exists on page load.
As you're shifting the eventListener up the hierarchy, you need to ignore clicks other than the desired element. This can be achieved with event.target and .contains():
if (document.querySelector('.profile').contains(event.target)) { }
So your final code would look like:
const body = document.querySelector('body');
body.addEventListener('click', function() {
if (document.querySelector('.profile').contains(event.target)) {
alert('js code works!');
}
})
The above ensures that when you click on your dynamically-generated elements your alert() will fire, but it won't fire when you click on any other element.
I can suggest two different methods. The first one is that you can write javascript codes after the html code. or wait for the document to be loaded using 'document.addEventListener('DOMContentLoaded', ...)'
document.addEventListener('DOMContentLoaded', function() {
document.querySelector('.profile').addEventListener('click',function=(){
alert('js code works!');
});
})

Reinitalize Dom after Ajax Request (.on input not working)

I have a bunch of text inputs that are dynamically created through a MySQL query.
At the bottom of my page I have this.. I had to use window.load instead of document.ready as the latter would not work
<script>
$(window).load(function() {
$('.<?php echo $sku; ?>').on('input', function() {
$('.'+$(this).attr('class')).val($(this).val());
});
});
It is my understanding that using .on should relate to both past and present dom objects, but this is not the case.
The (messy) html I'm currently dealing with is
<input type="text" class="mySKU18" id="inputsku" contenteditable="true" onkeydown="if (event.keyCode==13) saveToDatabase2(this,'itemnumber','mySKU18')" onClick="showEdit(this);"></input>
This is generated on the page load, and 'reset' using ajax if a button is clicked.
My issue is with the above script in relation to the html above.
Both HTML's are the same on the initial page load and ajax response.
Right now my solution to get this working is to reinitiate the script at the bottom of my ajax php script.
/// my php
?>
<script>
$('.<?php echo $sku; ?>').on('input', function() {
$('.'+$(this).attr('class')).val($(this).val());
});
</script>
This works and does not provide any console errors, but obviously is not ideal.
Anyone know what could be the issue and how to fix it?
Build your new text input elements like this and they will be in the DOM tree. You can build all of your new elements this way and use appendChild to link them together if you need them to be referenced in the DOM tree.
var text = document.createElement("input");
text.setAttribute('type', 'text')
text.setAttribute('id', 'yourID');
text.setAttribute('name', 'yourName');
text.setAttribute('class', 'yourClass');
text.setAttribute('style', 'yourStyle');
document.getElementById("yourParent").appendChild(text);

Can someone explain to me how this is possible? (Picture in comments)

So I'm trying to link up my html and javascript files in notepad++, but it isn't working properly.
I wanted to know how it is possible that it writes test, but doesn't remove the div. Can anyone explain this? Thanks in advance!
1, jQuery isn't linked. Meaning, you don't have <script type='text/javascript' src='myjQueryfile.js'></script> in your HTML, you'll want to put it before your script.
2:
Because the element with the ID of blue, doesn't exist yet. The DOM - basically the object of your HTML - has yet to be constructed when your script is run, which in this case is the top of the page, before blue comes into existence. You'll want to use an event to fix this, typically $(function(){ ... }); which will execute your code when the DOM is ready.
Also, document.write just writes code then and there, meaning exactly where the document.write calls is made, the HTML will be outputted.
You should have linked jquery. You're trying to use it without having it linked.
The script is loaded in the head. At the time the script executes the body of the document is not built, so nothing is removed. If you were to use the document.ready callback (and had properly included jQuery) it would work
$(function(){ $("#blue").remove(); });
A plain js version of this is
window.onload = function(){
var b = document.getElementById("blue");
b.parentNode.remove(b);
};
At the time the script runs, only the portion of the document up to the <script> tag has been loaded. You need to delay until the DOM has fully loaded before the script can target the DOM:
document.addEventListener("DOMContentLoaded", function(event) {
$("#blue").remove();
});

Div is not created before javascript run

I have a question about javascript/html.
First, I have this:
var post = document.body.getElementsByClassName("post");
var x=post[i].getElementsByClassName("MyDiv")[0].innerHTML;
I get from the debugger that x is not defined, it doesn't exists.
This javascript function runs onload of the body. I am sure that I gave the right classnames in my javascript, so it should find my div.
So, I read somewhere that sometimes javascript does not find an element because it is not yet there, it is not yet created in the browser ( whatever that means).
Is it possible that my function can't find the div with that classname because of this reason?
Is there a solution?
So, I read somewhere that sometimes javascript does not find an element because it is not yet there, it is not yet created in the browser ( whatever that means).
Browsers create the DOM progressively as they get the markup. When a script element is encountered, all processing of the markup stops (except where defer and async have an effect) while the script is run. If the script attempts to access an element that hasn't been created yet (probably because its markup hasn't been processed yet) then it won't be found.
This javascript function runs onload of the body.
If that means you are using something like:
<body onload="someFn()"...>
or perhaps
<script>
window.onload = function() {
someFn();
...
}
</script>
then when the function is called, all DOM nodes are available. Some, like images, may not be fully loaded, but their elements have been created.
If it means you have the script in the body and aren't using the load event, you should move the script to the bottom of the page (e.g. just before the closing body tag) and see if that fixes the issue.
Okay, instead of calling functions with
body onload, use jQuery's ready() function, or, if you don't want to use jQuery, you can use pure javascript, but this is up to you:
// jQuery
$(document).ready(function() {
var post = document.getElementsByClassName("post"),
x = post[i].getElementsByClassName("MyDiv")[0].innerHTML;
});
// JavaScript
window.onload = function initialization() {
var post = document.getElementsByClassName("post"),
x = post[i].getElementsByClassName("MyDiv")[0].innerHTML;
}
A few side notes, I don't know what the use of innerHTML
is, and also if you're doing a for loop with i then definitely
post that code, that's kind of important.
After some discussion, my answer seems to have worked for you, but you can also place your script at the end of your body tag as #RobG has suggested.

Removing a script tag with a specific content using jquery

I have a page that i dont have access to its an obvius site. I would like to remove a script html tag with a content. For now i have this but is not working. I am using userscripts like coding!
function main(){
var def = $('script[type="text/javascript"]').html();
$('script[type="text/javascript"]').each(function() {
if (def == 'document.write("<scr"+"ipt type=\'text/javascript\' src=\'http://storing.com/javascripts/"+(new Date()).getTime()+"/3e155555e1b26c2d1ced0f645e_1_1.js\'></scr"+"ipt>")')
$('script[type="text/javascript"]').remove();
}
}
UPDATE:
<script type="text/javascript">document.write("<scr"+"ipt type='text/javascript' src='http://somedomain.com/javascripts/"+(new Date()).getTime()+"/3e1a0cd37f25a6e1b26c2d1ced0f645e_1_1.js'></scr"+"ipt>")</script>
This is the whole script what i want to remove... it inserts a div that i am removing right now i just wanted to know if there is any other method. BUt as i see the only is the hosts file thing :)
I don't believe this will work, since a loaded script will already have run.
That said, you probably want something like this:
$('script').each(function() {
if (this.src.substring(0, 31) === 'http://storing.com/javascripts/') {
$(this).remove();
}
});
It's impossible to match the <script> tag based on the output of .html() because that only returns the contents of the element, and not the outer <script> element nor the element's attributes.
When a script is loaded in a page, it is evaluated and executed by the browser immediately after. After the script has been executed, the content of the script tag is irrelevant.
You might be able to achieve what you want by unbinding the events which might have been loaded by the script. Are there any events you want to disable?
If the script is in a certain domain and you want to block all traffic to it, you could add the following entry to your hosts file:
127.0.0.1 storing.com
This will prevent the request to reach it's destination.

Categories