Converting a Buffer to JSON and Utf8 Strings in Nodejs
Nodejs and browser based JavaScript differ because Node has a way to handle binary data even before the ES6 draft came up with ArrayBuffer. In Node, Buffer class is the primary data structure used with most I/O operations. It is a raw binary data that is allocated outside the V8 heap and once allocated, cannot be resized.
Before Nodejs v6.0, to create a new buffer you could just call the constructor function with new keyword:
let newBuff = new Buffer('New String');To create a new buffer instance, in latest and current stable releases of Node:
let newBuff = Buffer.from('New String');The new Buffer() constructor have been deprecated and replaced by separate Buffer.from(), Buffer.alloc(), and Buffer.allocUnsafe() methods.
More information can be read through official documentation.
Convert a Buffer to JSON
Buffers can convert to JSON.
let bufferOne = Buffer.from('This is a buffer example.');
console.log(bufferOne);
// Output: <Buffer 54 68 69 73 20 69 73 20 61 20 62 75 66
// 66 65 72 20 65 78 61 6d 70 6c 65 2e>
let json = JSON.stringify(bufferOne);
console.log(json);
// Output: {"type":"Buffer","data":[84,104,105,115,32,105,
// 115,32,97,32,98,117,102,102,101,114,32,101,120,97,109,
// 112,108,101,46]}The JSON specifies that the type of object being transformed is a Buffer, and its data.
Convert JSON to Buffer
let bufferOriginal = Buffer.from(JSON.parse(json).data);
console.log(bufferOriginal);
// Output: <Buffer 54 68 69 73 20 69 73 20 61 20 62 75 66
// 66 65 72 20 65 78 61 6d 70 6c 65 2e>Convert Buffer to Utf-8 String
console.log(bufferOriginal.toString('utf8'));
// Output: This is a buffer example..toString() is not the only way to convert a buffer to a string. Also, it by defaults converts to a utf-8 format string.
The other way to convert a buffer to a string is using StringDecoder core module from Nodejs API.