How to know there is any UTF8 character in a string with Javascript?

Question

I have a string such like that : "Xin chào tất cả mọi người". There are some Unicode characters in the string. All that I want is writing a function (in JS) to check if there is at least 1 Unicode character exists.

JavaScript strings do not "contain UTF-8" characters. They contain Unicode code-points (encoded as one code-point/character for Unicode in the BMP - whatever UTF-16/UCS-2 internal coding is an entirely different can of worms). So, now what is a "UTF-8 character"? Do you mean Unicode character not in the ASCII plane? — user2864740
– user2864740, Commented Feb 12, 2014 at 4:37

rvighne · Accepted Answer · 2014-02-12 04:35:04Z

11

A string is a series of characters, each which have a character code. ASCII defines characters from 0 to 127, so if a character in the string has a code greater than that, then it is a Unicode character. This function checks for that. See String#charCodeAt.

function hasUnicode (str) {
    for (var i = 0; i < str.length; i++) {
        if (str.charCodeAt(i) > 127) return true;
    }
    return false;
}

Then use it like, hasUnicode("Xin chào tất cả mọi người")

answered Feb 12, 2014 at 4:35

rvighne

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Comments

HeberLZ · Accepted Answer · 2017-07-20 19:09:04Z

2

Here's a different approach using regular expressions

function hasUnicode(s) {
    return /[^\u0000-\u007f]/.test(s);
}

edited Jul 20, 2017 at 19:09

answered Jul 13, 2017 at 23:09

HeberLZ

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1 Comment

StefansArya Over a year ago

The performance result will be different.. and your code doesn't detect the à .. your regex should be /[^\u0000-\u007f]/ :)

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