store a json object in ArrayBuffer

Question

Want to store a json object in ArrayBuffer

function stringToUint(string) {
    var string = btoa(unescape(encodeURIComponent(string))),
        charList = string.split(''),
        uintArray = [];
    for (var i = 0; i < charList.length; i++) {
        uintArray.push(charList[i].charCodeAt(0));
    }
    return new Uint8Array(uintArray);
}

function uintToString(uintArray) {
    var encodedString = String.fromCharCode.apply(null, uintArray),
        decodedString = decodeURIComponent(escape(atob(encodedString)));
    return decodedString;
}
var str = {'x':'aaaa'},
    enc = stringToUint(str),
    dec = uintToString(enc);

console.log(dec.x);

console.log(dec.x); is printing `undefined. Am I doing it wrongly ? here is jsfiddle http://jsfiddle.net/DQJyX/137/

score 7 · Accepted Answer · answered Mar 13 '16 at 14:49

Because stringToUint expects a string, and passing an object to it will convert the {'x':'aaaa'} to [Object object] and returns an array representing that object object, and hence on calling uintToString, the array is converted back to [Object object].

Simple solution is to use JSON.stringify to the object before passing it to function and then using JSON.parse to convert to original object.

function stringToUint(string) {
    var string = btoa(unescape(encodeURIComponent(string))),
        charList = string.split(''),
        uintArray = [];
    for (var i = 0; i < charList.length; i++) {
        uintArray.push(charList[i].charCodeAt(0));
    }
    return new Uint8Array(uintArray);
}

function uintToString(uintArray) {
    var encodedString = String.fromCharCode.apply(null, uintArray),
        decodedString = decodeURIComponent(escape(atob(encodedString)));
    return decodedString;
}
var str = {'x':'aaaa'},
    enc = stringToUint(JSON.stringify(str)),
    dec = JSON.parse(uintToString(enc));
    
document.write(dec.x);

How can I get back JSON from what we get from `Utils.stringToUint(JSON.stringify(str))` — Manish Kumar, Mar 13 '16 at 15:38

score 2 · Answer 2 · answered Mar 13 '16 at 14:47

in order for it to work you need, in the stringToUint function call to JSON.stringify.

function stringToUint(string) {
    var string = btoa(unescape(JSON.stringify(string))),
        charList = string.split(''),
        uintArray = [];
    for (var i = 0; i < charList.length; i++) {
        uintArray.push(charList[i].charCodeAt(0));
    }
    return new Uint8Array(uintArray);
}

function uintToString(uintArray) {
    var encodedString = String.fromCharCode.apply(null, uintArray),
        decodedString = decodeURIComponent(escape(atob(encodedString)));
    return decodedString;
}
var str = {'x':'aaaa'},
    enc = stringToUint(str),
    dec = uintToString(enc);

console.log(dec);

score 0 · Answer 3 · answered Nov 14 '19 at 07:49

This code for stringToUint is ~40% faster, benchmark link

function stringToUint(string) {
  const str = btoa(unescape(encodeURIComponent(string)))
  const uintArray = []
  const len = str.length

  let i = -1

  while (++i < len) {
    uintArray[i] = str.charCodeAt(i)
  }

  return new Uint8Array(uintArray);
}

store a json object in ArrayBuffer

3 Answers3