I’ve been experimenting with Unicode characters in JavaScript variable names and found some interesting behavior. While testing in different browsers, I discovered that some Unicode symbols work perfectly fine as variable names, but others throw errors.
For example, this code works without issues:
let мояПеременная = "test value";
let emoji😀variable = "happy face";
let 变量名称 = "chinese characters";
let ಬದಲಾವಣೆ = "kannada text";
console.log(мояПеременная + emoji😀variable + 变量名称 + ಬದಲಾವಣೆ);
However, when I try to use symbols like ◎ܫ◎ or as variable names, JavaScript throws syntax errors. What determines which Unicode characters are acceptable for variable naming in JavaScript? Is there a specific Unicode category or standard that defines valid identifier characters?
JavaScript uses the ECMAScript specification to determine which characters are valid for variable names. Specifically, there is a distinction between characters that can initiate a variable name and those that can be used subsequently. The initial characters must belong to actual Unicode letters (categories such as Lu, Ll, Lt, Lm, Lo) or connector punctuation like the underscore. In contrast, the symbols you experimented with, such as ◎ and , fall under the Symbol category and thus are not permitted. The variables that succeeded in your examples utilized legitimate letters from diverse writing systems, including Cyrillic, Chinese, and Kannada. While emojis can sometimes work as variable names due to their letter-like properties, this is not a universal rule for all emojis. For reliable information, you could explore Unicode character categories online to verify if a character can be used.
It’s all about Unicode categorization and how JavaScript handles identifier rules. Those syntax errors with symbols like ◎ܫ◎ or happen because JavaScript’s pretty strict about what counts as a valid identifier character. I’ve debugged this before - the issue usually comes from mixing real letters with decorative symbols. Your working examples use actual letters from different writing systems. Cyrillic, Chinese, and Kannada scripts have proper letter characters that JavaScript accepts as valid identifiers. Emojis are especially tricky since some contain Unicode sequences with valid letter components, while others are just symbols. I test individual characters using JavaScript’s built-in methods before putting them in production code. Honestly, I’d stick with traditional alphabetic characters from established writing systems instead of experimenting with decorative symbols. Browser compatibility can be inconsistent even when the spec technically allows certain characters.
yeah, this tripped me up when i first started using unicode in js too. those symbols ur struggling with aren’t actually “letters” according to unicode - they’re classified as symbols or marks. javascript only lets u use real letters for variable names, so decorative stuff like or math symbols won’t work.
as variable names, JavaScript throws syntax errors. What determines which Unicode characters are acceptable for variable naming in JavaScript? Is there a specific Unicode category or standard that defines valid identifier characters?