How to Convert JSON to base64 in JavaScript ?

Last Updated : 16 Apr, 2024

Base 64 is the encoding scheme that represents binary data in a printable ASCII format, commonly used for data serialization and transmission.

Table of Content

Using btoa function

In this approach, we're using btoa to encode a UTF-8 string representation of a JSON object. First, the JSON data is converted to a UTF-8 string using unescape and encodeURIComponent, and then btoa encodes this UTF-8 string to Base64.

Syntax:

const base64String = btoa(stringToEncode);

Example: The below example uses btoa function to convert JSON to Base64 in JavaScript.

JavaScript

const jData = {
    name: 'GFG',
    age: 30
};
const utf8Str = unescape(encodeURIComponent
    (JSON.stringify(jData)));
const res = btoa(utf8Str);
console.log(res);

Output

eyJuYW1lIjoiR0ZHIiwiYWdlIjozMH0=

Using Manual Conversion

In this approach, we're manually converting a JSON string to Base64. The function conversionFn encodes the UTF-16 characters of the JSON string into Base64 using a custom algorithm that follows the Base64 encoding table, including handling padding characters ('=').

Example: The below example uses Manual Conversion to convert JSON to Base64 in JavaScript.

JavaScript

const jData = {
    name: 'GFG',
    age: 30
};
const jStr = JSON.stringify(jData);
const baseTable = 
    'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/';

function conversionFn(str) {
    let res = '';
    let i = 0;
    while (i < str.length) {
        const c1 = str.charCodeAt(i++);
        const c2 = str.charCodeAt(i++);
        const c3 = str.charCodeAt(i++);
        const triplet = (c1 << 16) | (c2 << 8) | c3;
        const b64c1 = baseTable.
            charAt((triplet >>> 18) & 0x3F);
        const b64c2 = baseTable.
            charAt((triplet >>> 12) & 0x3F);
        const b64c3 = baseTable.
            charAt((triplet >>> 6) & 0x3F);
        const b64c4 = baseTable.
            charAt(triplet & 0x3F);
        res += b64c1 + b64c2 + b64c3 + b64c4;
    }
    const padding = str.length % 3;
    if (padding === 1) {
        res = res.slice(0, -2) + '==';
    } else if (padding === 2) {
        res = res.slice(0, -1) + '=';
    }
    return res;
}
const res = conversionFn(jStr);
console.log(res);