Incluindo o JS

Por último e mais importante, incluindo o JavaScript  para ser interativo com o usuário.

javascript/script.js

@@ -0,0 +1,151 @@
+const previousOperationText = document.querySelector("#previous-operacao");
+const currentOperationText = document.querySelector("#atual-operacao");
+const buttons = document.querySelectorAll("#conteiner-botao button");
+
+class Calculator {
+  constructor(previousOperationText, currentOperationText) {
+    this.previousOperationText = previousOperationText;
+    this.currentOperationText = currentOperationText;
+    this.currentOperation = "";
+  }
+
+  // adicionar dígito à tela da calculadora
+  addDigit(digit) {
+    console.log(digit);
+
+    // Verificando se o número já tem um ponto
+    if (digit === "." && this.currentOperationText.innerText.includes(".")) {
+      return;
+    }
+
+    this.currentOperation = digit;
+    this.updateScreen();
+  }
+
+  // processa todas as operações da calculadora
+  processOperation(operation) {
+
+    // Verificando se o valor atual está vazio
+    if (this.currentOperationText.innerText === "" && operation !== "C") {
+
+      // Alterar operação
+      if (this.previousOperationText.innerText !== "") {
+        this.changeOperation(operation);
+      }
+      return;
+    }
+
+    // Valores atuais e anteriores
+    let operationValue;
+    let previous = +this.previousOperationText.innerText.split(" ")[0];
+    let current = +this.currentOperationText.innerText;
+
+    switch (operation) {
+      case "+":
+        operationValue = previous + current;
+        this.updateScreen(operationValue, operation, current, previous);
+        break;
+      case "-":
+        operationValue = previous - current;
+        this.updateScreen(operationValue, operation, current, previous);
+        break;
+      case "*":
+        operationValue = previous * current;
+        this.updateScreen(operationValue, operation, current, previous);
+        break;
+      case "/":
+        operationValue = previous / current;
+        this.updateScreen(operationValue, operation, current, previous);
+        break;
+      case "DEL":
+        this.processDelOperator();
+        break;
+      case "CE":
+        this.processClearCurrentOperator();
+        break;
+      case "C":
+        this.processClearOperator();
+        break;
+      case "=":
+        this.processEqualOperator();
+        break;
+      default:
+        return;
+    }
+  }
+
+  // Altera os valores da tela da calculadora
+  updateScreen(
+    operationValue = null,
+    operation = null,
+    current = null,
+    previous = null
+  ) {
+    if (operationValue === null) {
+
+      // Anexar número ao valor atual
+      this.currentOperationText.innerText += this.currentOperation;
+    } else {
+
+      // Verificar se o valor é zero, se for apenas adicione o valor atual
+      if (previous === 0) {
+        operationValue = current;
+      }
+
+      // Adicionar o valor atual ao anterior
+      this.previousOperationText.innerText = `${operationValue} ${operation}`;
+      this.currentOperationText.innerText = "";
+    }
+  }
+
+  // Alterar operação
+  changeOperation(operation) {
+    const mathOperations = ["*", "-", "+", "/"];
+
+    if (!mathOperations.includes(operation)) {
+      return;
+    }
+
+    this.previousOperationText.innerText =
+      this.previousOperationText.innerText.slice(0, -1) + operation;
+  }
+
+  // Deletar o digito
+  processDelOperator() {
+    this.currentOperationText.innerText =
+      this.currentOperationText.innerText.slice(0, -1);
+  }
+
+  // Limpar operação
+  processClearCurrentOperator() {
+    this.currentOperationText.innerText = "";
+  }
+
+  // Limpar todas as operações
+  processClearOperator() {
+    this.currentOperationText.innerText = "";
+    this.previousOperationText.innerText = "";
+  }
+
+  // Processar uma operação
+  processEqualOperator() {
+    let operation = this.previousOperationText.innerText.split(" ")[1];
+
+    this.processOperation(operation);
+  }
+}
+
+const calc = new Calculator(previousOperationText, currentOperationText);
+
+buttons.forEach((btn) => {
+  btn.addEventListener("click", (e) => {
+    const value = e.target.innerText;
+
+    if (+value >= 0 || value === ".") {
+      console.log(value);
+      calc.addDigit(value);
+    } else {
+      calc.processOperation(value);
+    }
+  });
+});