JS in string to Base64 and base64 to string

Var str = ‘坂井泉水’;

   //console.log(encodeURI(str));
   //console.log(btoa(encodeURI(str)));

   //console.log(atob(btoa(encodeURI(str))));
   //console.log(decodeURI(atob(bcode(())))));


   / / string to base64
   Function encode(str){
     // encode the string
     Var encode = encodeURI(str);
     // Convert the encoded string to base64
     Var base64 = btoa(encode);
     Return base64;
   }

   // base64 to string
   Function decode(base64){
       // encode base64
       Var decode = atob(base64);
       // encoding to string
       Var str = decodeURI(decode);
       Return str;
   }

   Console.log(encode(str));
   Console.log(decode(encode(str)));  

JS in string to Base64 and base64 to string