string-replace.js

var str = "\\x{6211}\\x{53F8}\\x{5EFA}\\x{8BAE}\\x{52A0}\\x{5927}\\x{5185}\\x{89D2}\\x{534A}\\x{5F84}\\x{5230}R=0.4mm.";
str = str.replace(/\\x\{(.*?)\}/g, function(substring, p1){
    return String.fromCharCode(parseInt(p1, 16));
});
print(str);