Hashing with Asynchronous programming

hashing.js

/* --------- app.js ----------*/
// Import block class
const BlockClass = require('./block')

// Create a block object
const block = new BlockClass.Block("Test Block")

// Generate the block hash
block.generateHash().then((result) => {
    console.log(`Block Hash: ${result.hash}`)
    console.log(`Block: ${JSON.stringify(result)}`)
}).catch((error) => {
    console.log(error)
})

/* --------- block.js ----------- */
const SHA256 = require('crypto-js/sha256')

class Block {
    constructor(data) {
        this.id = 0
        this.nonce = 14444
        this.body = data
        this.hash = ""
    }

    generateHash() {
        let self = this;
        return new Promise(function(resolve, reject) {
            self.hash = SHA256(JSON.stringify(self)).toString()
            resolve(self)
        })
    }
}

module.exports.Block = Block