Convert a JSON object to ArrayBuffer

Question

How can I store a JSON object in an ArrayBuffer? I tried the code below.

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/

Ammar Hasan · Accepted Answer · 2016-03-13 14:49:01Z

6

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);

answered Mar 13, 2016 at 14:49

Ammar Hasan

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3 Comments

Manish Kumar Over a year ago

How can I get back JSON from what we get from Utils.stringToUint(JSON.stringify(str))

Ammar Hasan Over a year ago

using JSON.parse

anthumchris Jul 13 at 15:27

This answer is 10 years old, use TextEncoder

Zamboney · Accepted Answer · 2016-03-13 14:47:25Z

1

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);

answered Mar 13, 2016 at 14:47

Zamboney

2,00712 silver badges22 bronze badges

Comments

anthumchris · Accepted Answer · 2025-07-15 16:04:45Z

1

Since 2020, consider using TextEncoder:

const encode = (e => e.encode.bind(e))(new TextEncoder()) // reusable
const buffer = encode({ a:1, b:2, c:3 }).buffer
console.log('instanceOf:', buffer.constructor.name)
console.log('totalBytes:', buffer.byteLength)

edited Jul 15 at 16:04

answered Jul 13 at 15:15

anthumchris

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Comments

Stephen Richardson · Accepted Answer · 2019-11-14 07:49:57Z

-1

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);
}

answered Nov 14, 2019 at 7:49

Stephen Richardson

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