将字符串以UTF8进行转码

function toUtf8(str)
{  
    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;  
}