Symbol not displaying properly [closed] - validation

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The symbol is: ؤْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْْ
What's so special about this symbol and where did it come from?
What can be done to validate against such input? Or even better, how can such symbols be displayed properly (i.e. not letting them overlap over other elements) ?

Answer 1

Well since it seems to be not as trivial as I thought for others here is my answer.
This is called Combining Diacritical Marks.
To give you an example you can write a ä directly or as ä which results in "ä".
Now you can mess up with that signs like here: "ä̈̈̈̈̈̈", here I entered: ä̈̈̈̈̈̈
To protect yourself to such "unicode" attacks you could limit the count of unicode chars which are allowed to come after each other. I cannot give you an exact example since you tags don't give a hint about your server side language. If you have a plain english website you might try to limit it to ascii chars only. However I would not recomment that, since I would be not allowed to sign then with my name :-)
I would just limit the count of Unicode characters after each other. That might been done with regex.
If you just want to avoid that the Unicode characters "break out" of their container try using style="overflow:auto" which seems to limit the way how it is rendered.

Answer 2

I just copied the symbol to SQL Server and Visual Studio and found that the symbol got converted to
So it looks like the combination of ْ (which looks like an Arabic symbol)symbol which the browser is not able to recognize.
The symbol is Arabic Hamza symbol.
Also the same symbol is interpreted correctly by IE.
So it looks like that some browsers are not able to recognize the symbol.
EDIT:
To validate such input usually you can use some sort validation(like to restirct user to enter only ASCII characters) using languages like Javascript or PHP through which you can restrict the user to input the characters as per your choice.
Or even better, how can such symbols be displayed properly
If the browser cannot render the symbol as the one you have shown then as a workaround you can put some limit on those characters like put them inside a div with overflow:auto but that would not be a good solution. A better one would be to use a validation script.

Answer 3

It strange that, on screen you will see only 1 character followed by a line drawn from nowhere.
But when inspected with chrome, It is actually characters with 1st character having Unicode 1572, followed by 161 characters that draws line having Unicode 1618 ! And after that there is Unicode (or ASCII code) 32 for space.

Answer 4

I am not sure if parsing your symbols in Javascript is gonna be helpful but here is a script that does that:
var text = 'your symbol goes here',
regex1 = /(?:[\u0624|\u0652])/g,
result;
// note that the symbol comprises of the letter and the repeated diacritics;
// to remove the symbol completely:
result = text.replace( regex1, '');
Here is a way to see what kind of characters are included in the symbol and how these chars made it looked very weird (it’s using javascript regex):
https://regex101.com/r/yW4aM8/3
You may wanna use meta tag: charset=UTF-8 to render the entire symbol correctly on all browsers than trying it only on IE. I would say the only reason your symbol looks weird is because the diacritics (the repeated chars) are not used correctly, otherwise, the chars included are all legit. I wouldn’t really be surprised if this symbol is just someone trying to misuse a form input or something for the same effect.
The symbol is using pure Arabic characters, and just for you to know the range of this language’s characters in the unicode are as follows (javascript regex) and available at unicode.org:
/[\u0600-\u06FF]/g
/[\u0600-\u06FF]/g.exec( ‘text here’ );
// it's advised that you wrap the Arabic words in spans to control and show them correctly, do the following:
'text includes arabic words'.replace(/(?:([\u0600-\u06FF]+))/g, '<span class="xyz">$1</span>';
and the css would be:
.xyz { unicode-bidi: bidi-override; }
I hope that helps a bit.
good luck.

Answer 5

$ echo -n ؤْْ | recode utf8..dump
UCS2 Nem Descripción
0624 wH arabic letter waw with hamza above
0652 0+ arabic sukun
0652 0+ arabic sukun
0652 0+ arabic sukun
[...lots of repeated lines...]
0652 0+ arabic sukun
That's the arabic waw (w) with a lot of diacritics: 1 hamza (precomposed as the character waw with hamza above) and about 160 repeated sukun diacritics.