I want to validate a text input field in a html page to accept only Cyrillic letters. I have written the validation code in JavaScript using regular expression like this:
var namevalue = document.getElementById("name")
var letters = /^[А-Яа-я]+$/;
if (namevalue.matches(letters)) {
alert("Accepted");
}
else {
alert("Enter only cyrillic letters");
}
This code works fine for all cyrillic letters except Ё ё
The problem why ё is not working because it's out of range Aа-Яя. Aа-Яа is in a Basic Cyrillic alphabet [0430-044F], but ё isn't in that Basic Cyrillic alphabet. ё belongs to Cyrillic extensions [0400-045F]. Because, JavaScript regexs engine compares not by letters itself but by its charcodes, so ё just is out of range.
Since I presume you mean modern Russian language where despite ё is rare but still in wide use
I may suggest this solution
var namevalue = document.getElementById("name")
// please note that I added to your pattern "еЁ".
// now this matches all Russian cyrillic letters both small and caps
// plus ё and Ё
var letters = /^[А-Яа-яёЁ]+$/;
if (namevalue.matches(letters)) {
alert("Accepted");
}
else {
alert("Enter only cyrillic letters");
}
Unfortunately the problem with A-Я and Ё buried deep in Unicode specification. There is no plain and simple solution. So for robust programming you need always be prepared for such cases.
That Ë isn't necessarily in the cyrillic alphabet, and as such, not caught in the А-Яа-я range you're using.
Is your Ë Cyrillic: U+0401 or just Latin: U+00CB?
If you also want to catch non-cyrillic Ë's , you may want to add this range to your regex: À-ÿ:
alert(JSON.stringify("Ëë".match(/^[À-ÿ]+$/)))If you just want to catch Ë's in the Cyrillic alphabet, try this:
Instead of starting your range at U+0410 (А), start it at U+0400 (Ѐ) and end it at U+045F (џ):
alert(JSON.stringify("Ёё".match(/^[Ѐ-џ]+$/)))(This last range should include the full Cyrillic alphabet.)
Source: Unicode character codes. You can use this page to check what range(s) you need to add to your regex.
