app.js

class Calculator {
    constructor(previousOperandTextElement, currentOperandTextElement) {
        this.previousOperandTextElement = previousOperandTextElement;
        this.currentOperandTextElement = currentOperandTextElement;
        this.clear();
    }

    clear() {
        // clear button functionality
        this.currentOperand = '';
        this.previousOperand = '';
        this.operation = undefined;
    }

    delete() {
        // delete button functionality
    }

    appendNumber(number) {
        if (number === '.' && this.currentOperand.includes('.')) return;
        this.currentOperand = this.currentOperand.toString() + number.toString();
    }

    chooseOperation(operation) {

    }

    compute() {

    }

    updateDisplay() {
        this.currentOperandTextElement.innerText = this.currentOperand;
    }
}

const numberButtons = document.querySelectorAll('[data-number]');
const operationButtons  = document.querySelectorAll('[data-operation]');
const equalsButton = document.querySelector('[data-equals]');
const deleteButton = document.querySelector('[data-delete]');
const allClearButton = document.querySelector('[data-all-clear]');
const previousOperandTextElement = document.querySelector('[data-previous-operand]');
const currentOperandTextElement = document.querySelector('[data-current-operand]');

const calculator = new Calculator(previousOperandTextElement, currentOperandTextElement);

numberButtons.forEach(button => {
    button.addEventListener('click', () => {
        calculator.appendNumber(button.innerText)
        calculator.updateDisplay()
    });
});