JSON.stringify and unicode characters

Question

I have to send characters like ü to the server as unicode character but as a string. So it must be \u00fc (6 characters) not the character itself. But after JSON.stringify it always gets ü regardless of what I've done with it.

If I use 2 backslashes like \\u00fc then I get 2 in the JSON string as well and that's not good either.

Any trick to avoid this? It's very annoying.

Ok, I forgot: I can't modify the string after JSON.stringify, it's part of the framework without workaround and we don't want to fork the whole package.

Answer 1

If, for some reason, you want your JSON to be ASCII-safe, replace non-ascii characters after json encoding:

var obj = {"key":"füßchen", "some": [1,2,3]}

var json = JSON.stringify(obj)
json  = json.replace(/[\u007F-\uFFFF]/g, function(chr) {
    return "\\u" + ("0000" + chr.charCodeAt(0).toString(16)).substr(-4)
})

document.write(json);
document.write("<br>");
document.write(JSON.parse(json));

Answer 2

This should get you to where you want. I heavily based this on this question: Javascript, convert unicode string to Javascript escape?

var obj = {"key":"ü"};
var str1 = JSON.stringify(obj);
var str2 = "";
var chr = "";
for(var i = 0; i < str1.length; i++){
    if (str1[i].match(/[^\x00-\x7F]/)){
        chr = "\\u" + ("000" + str1[i].charCodeAt(0).toString(16)).substr(-4);
    }else{
        chr = str1[i];
    }
    str2 = str2 + chr;
}  
console.log(str2)

I would recommend though that you look into @t.niese comment about parsing this server side.