JSFiddle - React, Tailwind, and code Playground

HTML

<input type = "text" value = "" name = "receiverAccount" id= "recacc"> 
    <button>Send Transaction</button>

JavaScript

var input = document.getElementById('recacc')
const preparedParameters = {
	user: 'kkk',
	amount: 100500
}

document.querySelector('button').addEventListener('click', function () {
	const finalParameters = Object.assign({}, preparedParameters, {
		targetUser: input.value
	})
  alert(JSON.stringify(finalParameters, null, '  '))
}, false)