1

str = str+'';

1
2
3
4
56
7
8
9
1011
12
13
14
1516
17
18
19
2021
22
23
24
2526
27
28
29
3031
32
33
34
3536
37
38
39
4041
42

// Form a string with a form of the Han character for "you" surrounded by the letters A and Z
var str = 'A\ud87e\udc04Z'; // Including two "surrogates" which are used to form a single character in Unicode (so the count of this should be 3, not 4 as str.length will give)
// var str = 'A你Z'; // If your blogging software won't mess with the Unicode, you can try this equivalent example as well (should be 3, not 4 as str.length will give)
 
alert(  strlen(str)
);
 
// Note that the exceptions will only be thrown if the string is poorly formed Unicode (something unlikely unless it was deliberate--e.g., try taking out one of the surrogate pairs above).
// Also note that although it will indeed be rare, especially for Western scripts, that str.length would not handle the situation correctly, in order to support handling of all languages that can be expressed in Unicode, the following is necessary. 
function strlen (str) {
        function getWholeChar (str, i) {
                var code = str.charCodeAt(i);
                if (0xD800 <= code && code <= 0xDBFF) { // High surrogate(could change last hex to 0xDB7F to treat high private surrogates as single characters)                        if (str.length <= (i+1))  {
                                throw 'High surrogate without following low surrogate';
                        }
                        var next = str.charCodeAt(i+1);
                        if (0xDC00 > next || next > 0xDFFF) {                                throw 'High surrogate without following low surrogate';
                        }
                        return str[i]+str[i+1];
                }
                else if (0xDC00 <= code && code <= 0xDFFF) { // Low surrogate                        if (i === 0) {
                                throw 'Low surrogate without preceding high surrogate';
                        }
                        var prev = str.charCodeAt(i-1);
                        if (0xD800 > prev || prev > 0xDBFF) { //(could change last hex to 0xDB7F to treat high private surrogates as single characters)                                throw 'Low surrogate without preceding high surrogate';
                        }
                        return false; // We can pass over low surrogates now as the second component in a pair which we have already processed
                }
                return str[i];        }
        for (var i=0, lgth=0; i < str.length; i++) {
                if ((chr = getWholeChar(str, i)) === false) {continue;} // Adapt this line at the top of any loop, passing in the whole string and the current iteration and returning a variable to represent the individual character; purpose is to treat the first part of a surrogate pair as the whole character and then ignore the second part
                lgth++;
        }        return lgth;
}

1

return (string+'').length;

1
2
3

function strlen (string) {
    return (string+'').length;
}

1

return String(string).length;

1

return ("" + string).length;