If I have a text area that can display user entered input. How should I encode it to prevent any security issues?
For instance suppose I have this:
<!DOCTYPE html>
<html>
<head>
<title>Title</title>
</head>
<body>
<form>
<textarea></textarea><script>alert('Hello');</script></textarea>
</form>
</body>
</html>
How should I encode the contents of the textarea so that it shows the </textarea><script> as text rather than running it?
I'm using ASP.Net, but I'm really after a general answer for HTML.
This is different to "Rendering HTML inside textarea" as I don't want to render HTML inside the textarea where as with that question they did.
You use HTMLEncode.
<textarea><%= Server.HtmlEncode("</textarea><script>alert('Hello');</script>") %></textarea>
Or
TextBox1.Text = Server.HtmlEncode(myString);
If you want to post <script>the tag will be picked up.
Displaying a tag as text type < and > they will be displayed as < > Link
So the html would look like:
<textarea> </textarea> <script>alert('Hello');</script> </textarea>
but #VDWWD answer is a better solution for asp.net development.
Related
I am trying to find a way to make my code appear as text in HTML but in the way you see the code on here
I want my code to appear like this on the website
right now when I run the code, I got it to appear as text but it looks like this:
<h1>"this is a heading"</h1>
But I want it to look like this:
<h1>"this is a heading"</h1>
basically, I'm trying to get the code that appears on my website to look like I took a screenshot of the code editor and put it on the site
If you don't understand what I'm trying to ask please ask me and I will try to elaborate further
quick answer will be make a div, give it a specific background color, use overflow properties to make it scrollable. Use monospace font and give specific color and background color. That'll look like a screenshot you took from code editor. but it'll be scrollable and it's necessary if you have a lot of codes.
<h1><span style="background-color: #e4e6e8;">"this is a heading"</span>
</h1>
A simple inline style should be sufficient for a one off but if you wanted to repeat it then defining a class either in the <head> section or by defining the class in a stylesheet and adding a link again in the <head> section would be a better approach.
Classes can be re-used easily and if you need to make changes then you only need to change the class attributes/definition and upon reload you changes are reflected everywhere the class was used/inserted.
This is simplest way for your apparently simple need.
<h1><span style="background-color: #e4e6e8;">"this is a heading"</span></h1>
To learn more about styling HTML why not follow this link perhaps Styling HTML Elements # Tutorial Republic (Sadly no affiliation!)
I'm not sure if I understand your question but You can use the <pre>...</pre> tag to obtain code like text :
<!doctype html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>My document</title>
<script>
function escapeHTML(html){
const chars = {'<':'<','>':'>'};
let s = html;
s = s.replace(/[<>]/g, m => chars[m]);
return(s + "<br>");
}
</script>
</head>
<body>
<h1 style="font-size:1.6em">"Title"</h1>
<div style="font-size:1.4em">code</div>
<pre id="output" style="font-size:1.4em;display:inline-block;background-color:#cccccc">
Your code is written here
</pre>
<script>
let display = document.getElementById("output");
display.innerHTML = escapeHTML('<h1 style="font-size:1.6em">"Title"</h1>');
display.innerHTML += escapeHTML(' <div style="font-size:1.4em">code</div>');
display.innerHTML += escapeHTML(' <pre id="output" style="font-size:1.4em;display:inline-block;background-color:#cccccc">');
display.innerHTML += escapeHTML(' Your code is written here');
display.innerHTML += escapeHTML(' </pre>');
</script>
</body>
</html>
I'm very new to Javascript and HTML but I wondered if there was a way you could make your webpage display the same way as your code. Such as if you had something like this:
<html>
<body>
<input type="button" value="Text">
<b>Hello world Hello<b>
</body>
</html>
Is there some sort of code I can put in to make it display just like that on the webpage. When I try it there aren't that many spaces between the world and Hello.
Put that in a pre tag
<pre>hello hello</pre>
pre tags keep spacing
I would like to get the same result as below but without the duplication (the same link appears twice):
<html>
<body>
http://www.w3schools.com
</body>
</html>
Is it possible in static HTML without Javascript?
You can do this without duplication using CSS selectors,
by using the attr function in CSS.
In your style sheet you can add this:
a::after {
content: attr(href);
}
For your example in the question:
<html>
<style>
a::after {
content: attr(href);
}
</style>
<body>
Some text
</body>
</html>
And it displays the link after Some text.
The HTML standard (a) only allows certain things to be placed in a href URL itself, and a "please use the textual description as the link" marker isn't one of those things.
You're right that it would save a lot of duplication, though most people may think that the textual description of a link should be a little more human-readable than a link. You wouldn't, for example, want to see the following in your web page:
http://www.google.com/patents?id=vmidAAAAEBAJ&printsec=frontcover&dq=database&hl=en&sa=X&ei=tN-0T-TtKu3TmAWNq7DiDw&ved=0CDUQ6AEwAA
Having said that, you can do it with CSS, specifically by using after to add elements containing the textual href attribute to the document. I'd suggest limiting it to a specific class so that you're not modifying every single a tag that you have, something like:
<html>
<style>
.add-link::after {
content: " (" attr(href) ")";
}
</style>
<body>
<a class="add-link" href="http://www.example.com">Link added</a>
<p />
No link added
</body>
</html>
The first link will have the link text added, the second will not. Unfortunately that won't solve the problem of monstrously large URIs (see above) being placed on the page as text, but you at least have the option of not attaching the add-link class on those):
(a): The HTML5 standard specifies the A element here and the URI specification here.
You can't, you'll either have to use JavaScript or keep it as it is.
No, there is no way to remove the duplication with only static html.
It is also not neccessary. Many Webpages use PHP or something like this and to make links in PHP is easy :)
PHP example:
<?php echo $item->link; ?>
Actually a good way of formatting a link is:
<html>
<body>
w3schools.com
</body>
</html>
This is a very strange problem I've been struggling with for a few days. At first I thought it was related to something in our application, but I've stripped it down to the simplest html page and it's still happening. Basically anytime I add a tag to a page the html after it gets rendered as it's value. <textarea></textarea> fixes the issue, but I don't understand why. I'm at a loss here, it has to be something really simple that I just don't know.
In the following example the paragraph tags show up as the value of the textarea.
I'm using IE8.
<html>
<head>
<title>About</title>
</head>
<body>
<textarea/>
<p align="center">
test
</p>
<p align="left">
test
</p>
</body>
<textarea> is not a self-closing tag. It should be re-written as <textarea></textarea>
I am assuming you trying to have the paragraphs appear after the textarea. Try not using the textarea tag as an empty tag.
<textarea></textarea>
<p align="center">
test
</p>
<p align="left">
test
</p>
I believe Textarea requires an opening and closing tag - at least that's how it's presented here:
textarea at w3schools
I had this problem too. I realized I had forgotten to give a name attribute to my textarea like I did all my other inputs so that the PHP script could collect it all and send it to an SQL table.
Once I gave it a name, it magically stopped chopping off the closing tag and making it a self closing tag which got ignored by the browser until it bumped into the closing tag of a textarea with a name attribute, swallowing up everything in between. Hopefully this sheds more light on the issue too, as putting text in between the closing tags wasn't an ideal option for me.
Closed. This question needs to be more focused. It is not currently accepting answers.
Want to improve this question? Update the question so it focuses on one problem only by editing this post.
Closed 3 years ago.
Improve this question
I want to place an example of code without the tags being processed?
Xmp tag will work:
<xmp>
...code...
</xmp>
ETA:
As of this writing this still works in all major browsers, but as others have pointed out it has officially been obsoleted in HTML5 [link]. Browsers could stop rendering it any day without warning or notice and it should be avoided for production sites. Still, there is no replacement that doesn't involve HTML encoding your string manually or using iframe trickery. It still has a place in my personal utility page tool-belt, but I would not consider it for a client.
The <pre> tag allows you to display text with whitespaces and line breaks as-is. Also, code must be entity-encoded:
For example, the code sample
<html>
<head><title></title></head>
<body></body>
</html>
will become
<pre><html>
<head><title></title></head>
<body></body>
</html></pre>
< encodes into < & encodes into &
PHP htmlentities does the job:
<pre><?php echo htmlentities($code) ?></pre>
<textarea> does the job too: it also allow the code to be copied.
To present code in HTML typically one would use the <code> tag.
Your question isn't very clear, and I don't know what you mean by "without the tags being processed". If you're saying that you want to present a fragment of HTML as code in an HTML page (for example), then you need to "escape" the HTML tags so that the web client doesn't attempt to parse them.
To do this, you should use the entity > for the greater-than angle bracket, and < for the less-than bracket.
Try:
<xmp></xmp>
or
<code></code>
for exemple:
<pre>
<xmp><!-- your html code --></xmp>
</pre>
<pre>
<code><!-- your html code --></code>
</pre>
bye
put it in a text area, its an html tag that will prevent all text inside him to be rendered
If you're using an XHTML <!DOCTYPE> declaration, then you could use CDATA sections:
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en" >
<head>
<title>My Example</title>
</head>
<body>
<h1>Example!</h1>
<pre><code>
<![CDATA[
<div>
<ol>
<li>a</li>
<li>b</li>
<li>c</li>
</ol>
</div>
]]>
</code></pre>
</body>
</html>
Note that you'll want to use a .xhtml file extension and you'll want to consider serving these documents with a Content-Type: application/xhtml+xml header.
The only thing I can think of is just converting all your ‘<’ and ‘>’ to ‘<’ and ‘>’ respectively
Beyond putting your code in 'pre' tags and escaping th '<' and'>' you may want to look as syntax highlighting. A good library for this was written by Alex Gorbatchev.
http://alexgorbatchev.com/SyntaxHighlighter/
Run the HTML you wish to display though htmlspecialchars() to properly escape the code you wish to display if you're using PHP. Do NOT use htmlentities() because your browser will choke on extended characters. Just make sure your page's encoding is set correctly in the <META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=UTF-8"> if you are outputting UTF-8 for example.
Good luck.
You can use textarea with this way.
<textarea class="form-control" rows="25">
<form action=".. " method="post" id="postForm">
<table>
<tr>
<td>Name:</td>
<td><input type="text" name="name" id="name" value="Customer Name" /></td>
</tr>
</table>
</form>
</textarea>
Note this use Bootstrap 3, if you want pure html remove textarea class and rows attribute.
Make it a comment.
<p>This will be rendered.</p>
<!-- from here on, this is a comment
<p>This won't be rendered.</p>
end of comment -->
<p>This will be rendered too.</p>
This works like a gem. I am trying to get the code on the HTML page. We need to use the combo as below. I have tested this as well.
<xpm>
<pre>
#include<stdio.h>
void fun(){
printf("%s","yooo");
}
fun();
</pre>
</xpm>