How to replace non-Ascii characters from input with something else in JavaScript

Question

I am implementing a chat-function to a JavaScript game using WebSocket. I want to replace non-ascii characters the user has written in the input textfield with other letters. Ä is replaced with a and Ö is replaced with o. And every other non-ascii characters should be replaced by "".

var message = document.getElementById("write_message").value;
message = message.replace(/ä/g, "a").replace(/ö/g, "o");
message = message.replace(/^[\000-\177]/g, "");
ws.send("M" + message);

I tried even simpler versions of the above code, but somehow all user input seemed to be replaced. Even ascii-characters. I found the regular expression from another Stackoverflow question.

encodeURIComponent?

BlueRaja - Danny Pflughoeft
– BlueRaja - Danny Pflughoeft

2017-10-27 18:51:45 +00:00
Commented Oct 27, 2017 at 18:51 — BlueRaja - Danny Pflughoeft
– BlueRaja - Danny Pflughoeft, Commented Oct 27, 2017 at 18:51

collapsar · Accepted Answer · 2013-04-17 14:23:20Z

4

you have to know the charset of the supporting html page. depending on whether it's unicode or some 8bit charser, use \uzzzz or \xzz to match chars where z represents a hex digit.

example: message = message.replace(/^[\u0080-\uffff]/g, ""); ascii-fies unicode text.

answered Apr 17, 2013 at 14:23

collapsar

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2 Comments

Teemu Leivo Over a year ago

I checked from Chrome's settings that it uses unicode(utf-8). I tried to replace them with "x" according to your code, but it only replaces the first one. "ä" becomes "x" as it should be. However "eä" stays the same. Also "ää" changes to "xä". What could be the problem?

collapsar Over a year ago

you must remove the caret (^) from your regex as it matches the beginning of the string.

Jukka K. Korpela · Accepted Answer · 2013-04-17 18:03:49Z

1

Your code is correct except that the circumflex ^ must appear after the left bracket [ in order to indicate negation. Otherwise it means something completely different.

However, I think you actually want to map uppercase Ä and Ö to A and O instead of deleting them. For this, you would use

message = message.replace(/ä/g, "a")
                 .replace(/ö/g, "o")
                 .replace(/Ä/g, "A")
                 .replace(/Ö/g, "O")
                 .replace(/[^\000-\177]/g, "");

answered Apr 17, 2013 at 18:03

Jukka K. Korpela

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