Develop Reference

Dynamically submit form and show the value of the input without reloading

I want to create a fully dynamic chat UI for my website,
But it reloads the whole page if a person submits the button this will directly show the div
<div class="messeging" id="msg">
<?php print $message->getName() ." : " . $chat->message . ""; ?>
</div>
Without reload msgs are save in some xml file path like example (../user/xml)
HTML
<form action="action.php" method="post">
<input type="text" id="input" value="php echo">
<input type="submit" value="send" onclick="showDiv()">
</form>
<div class="messeging" id="msg">
<?php print $message->getName() ." : " . $chat->message . ""; ?>
</div>
i don't know javascript/ajax well how to solve this

Try jquery ajax, on submit button send last msg for save into db and fetch all record and show them into chat page. so each time you send msg it will fetch all msg. if you don't know about how ajax work then let me know.

Begin by looking at the event on forms called 'onSubmit'. https://developer.mozilla.org/en-US/docs/Web/API/GlobalEventHandlers/onsubmit
Once you understand that, you can 'event.preventDefault()' in your 'onSubmit' method handler. Or in English, keep a form's default behavior to submit to the action from occurring.
After preventing the default action, you will need to do something with the form, and the easiest in latest browsers is to use the fetch API. https://developer.mozilla.org/en-US/docs/Web/API/Fetch_API
You should be able to submit the data in the form to some endpoint that returns the HTML you wish to inject.
Once the HTML has been successfully returned, simple document.createElement methods with append (https://developer.mozilla.org/en-US/docs/Web/API/ParentNode/append) will need to be used.
Good luck learning the web!

How to autopopulate a text box in html and php

So I have a page where a new user can input a username pswrd ect. then they fill out some information. An admin can then go and see whos registered and If so desired can go and edit the information entered by the user. What happens is when the admin clicks a button that redirects them to the schedule page I want the text fields to already be populated with all the information. I have confirmed with echo statements that I do have all the correct information at button press, I just cant get the text fields to update when the page loads.
Here is an example of one of the text boxes
<input type="text" id = "textBoxSchedule" name="email" placeholder="Email" value="<?php echo $email?>" required>
I have correctly set the value of $email, but what my guess is, is that HTML runs, creates the text box and then the PHP runs so its set after the value is created.
Thank you for your help!
EDIT:
Ok so heres how I get the information. From the admin page, I know what user I want to edit. So I pass that user name value through the $_SESSION variable and then I can use that one piece of information to get the rest of the text fields. Im not sure if this will have an affect or if its something I can utalize but the text boxes are below a header of:
<form action="<?php echo htmlspecialchars($_SERVER['PHP_SELF']);?>" method = "post">
(im partner coding this and he wrote a majority of this so im still working on understanding it all.)

Try using javascript for it.
<input type="text" id = "textBoxSchedule" name="email" placeholder="Email" required>
<?php echo "<script>myFunction(".$email."); </script>" ?>
The JS is ~
myFunction(x){
document.getElementById('textBoxSchedule').value = x;
}

Don't have enough reputation to comment, so I'll post an answer
<?php echo $email?>
You forgot the semicolon ( ; ) and you didn't leave a space before ?>
Also although it's not false, you should not put spaces before and after = symbol in html attributes
id = "textBoxSchedule"
Lastly I presume you reload the page and you don't expect php to run in client's browser?

I’ve tested your script on a blank php page with the following code:
<?php
$email = "test#email.com";
?>
<input type="text" id = "textBoxSchedule" name="email" placeholder="Email" value="<?php echo $email?>" required>
And I’ve managed to get the text box showing properly.
If you still have a problem showing your text box, you might want to double check the value of your $email variable of the code prior and after the example you’ve given us.

Reading in Data from HTML Javascript form

I am creating a website backed by a database. I have created my forms that collect the information but now i need to read in the input from the form when user clicks submit and process it for mySQL. I am having my form action be a new page but I can't figure out how to read in value from the previous page. My Form code looks like this:
<div data-wrapper-react="true">
<span class="form-sub-label-container" style="vertical-align:top;">
<input type="text" id="first_3" name="q3_fullName3[first]" class="form-textbox validate[required]" size="10" value="" data-component="first" />
<label class="form-sub-label" for="first_3" id="sublabel_first" style="min-height:13px;"> First Name </label>
</span>
When user hits submit the action for this page is connect.php. I am not sure how to read in the value there. I tried this following command:
document.getElementById("first_3").value;
This just displays the code on blank html page for connect.php and not read in the values. The data from the forms needs to be processed into different tables if someone can help with that as well that would be great. Thanks

Form handling, in the way you are describing, is something you do server-side. PHP is handled on the server first where PHP tags can be evaluated to HTML, then this is returned to the browser. You would not handle form input from javascript, until after your PHP has done something with it. Here is a refresher: https://www.w3schools.com/php/php_forms.asp
<?php echo $_POST["q3_fullName3[first]"]; ?> would output the value into the HTML page allowing you to do something like this:
console.log("<?php echo $_POST["q3_fullName3[first]"]; ?>");
If you view source of the HTML, you will notice the PHP tag is gone and replaced with the form field value.
It sounds like you might want to get a book about PHP + MySQL since interacting with a database is a more advanced topic. I can recommend this one:
https://www.amazon.com/Learning-PHP-MySQL-JavaScript-Javascript-ebook/dp/B00QUBHNFI/ref=mt_kindle?_encoding=UTF8&me=

Php code to modify a document element

I am trying to build a PHP webpage with the following behaviour:
1- A client access the webpage (that contains some buttons);
2- When the webpage is loaded, the PHP script opens a file stored on the server and, based on the information in this file, enables/disables some of the buttons, so that the client can see the webpage with the correct buttons enabled or disabled.
To enable/disable buttons, I know I can use javascript, while to read the file on the server I use PHP as stated above.
How do I put the two things together? Or should I use a PHP code equivalent to the following javascript line:
<script>document.getElementById("button1").disabled = true;</script>
At first I thought that inserting this line in the PHP code was the solution, but then I found out that this can't work for obvious reasons.
Thanks for the help!
Is it correct if I add the following javascript function in the head section of my webpage?
<script>
function enableButtons() {
<?php
if($state=="state1") {
echo 'document.getElementById("button1").disabled = true;';
}
else if($state=="state2") {
echo 'document.getElementById("button2").disabled = true;';
}
?>
}
</script>
I call the enableButtons() function when loading the page by using
<body onload="enableButtons()">
The php code above is just an example, the number of states and buttons is higher, that's why I would like to use this solution.

The common thing to do is to have php read the settings file, and echo the "disabled" attribute on the buttons before sending the output to the user browser. You can get more info about the attribute here here.
You do not need javascript.
Do something like this:
<button type="button" <?php if($state === 'state1') echo 'disabled'; ?>>Button text</button>

Usually you send to the client the buttons already disabled and use js to respond to any event that happens after sending the page, like selecting a combo box value..
You can omit the code, using an if sentence, or hide them using css. First approach is preferred.

Script
<script>
function isValid(f){
if(f.test.value==''){
alert('please enter name');
return false;
}else{
$(".bbutton").html("Processing please wait");
return true;
}
}
</script>
HTML
<form method="post" onsubmit="return isValid(this);">
<input type="hidden" name="te">
<input type="text" name="test">
<div class="bbutton">
<input type="submit" value="send">
</div>
</form>
When you submit the form then it will automatically hide the submit button to avoid pressing again and again, and you can redirect it to other page. May be this idea helpful.

How to make XSS vulnerable box

I wanna make a little input box where a user can submit a code and it happen like i they put
<script>alert("this is an alert")</script>
then a alert would pop up on the page
I need this for education purposes
<form><input type="text" name="xss"><input type="submit"></form>
<p>Result: <?= $_GET['xss'] ?></p>
Thats what i have tried but it doesnt work and w3c does not cover how to MAKE an XSS vulnerable input

There are several ways to do this. As one person suggested you could indeed use eval(). Just like the following:
<input type='text' id='vulnBox' value="alert('hello');"/>
<button onclick="eval(document.getElementById('vulnBox').value)">test</button>
Here's the corresponding fiddle example JSFiddle
If your interaction is more client to server then you could use $_GET in php to read your malicious javascript from the url and output into the contents of the page.
So someone would visit the page with a URL like:
yoursite.com?xss=%3Cscript%3Ealert()%3C%2Fscript%3E
and your php file would contain:
<?php echo urldecode($_GET['xss']); ?>
Hope this helps!