JavaScript 代码笔记 —— 常用 String 函数

JavaScript 代码笔记 —— 常用 String 函数

String.toUtf8 = function(str){   
//Unicode 编码转换为 UTF-8 编码，该方法不支持 Unicode 编号大于 0xFFFF 的字符串,str.length方法会将编码大于 0xFFFF 的字符识别为 2 个字符
    var out, i, len, c;    
    out = "";    
    len = str.length;    
    for(i = 0; i < len; i++) {    
        c = str.charCodeAt(i);
        if ((c >= 0x0001) && (c <= 0x007F)) {    
            out += str.charAt(i);    
        } else if (c > 0x07FF) {    
            out += String.fromCharCode(0xE0 | ((c >> 12) & 0x0F));    
            out += String.fromCharCode(0x80 | ((c >> 6) & 0x3F));    
            out += String.fromCharCode(0x80 | ((c >> 0) & 0x3F));    
        } else {    
            out += String.fromCharCode(0xC0 | ((c >>  6) & 0x1F));    
            out += String.fromCharCode(0x80 | ((c >> 0) & 0x3F));    
        }    
    }    
    return out;    
}