计算器项目 - 卡住了 - javascript

Question

我坚持让这个计算器工作...所以如果我按等号键，我的计算器基本上可以工作，（1 + 2 = 3）...但我想让它工作，即使用户是只按运算符，例如 1+4/5+2，这样即使只按运算符也会自动计算。

这是我的代码：

// DOM elements 
const numberButton = document.querySelectorAll('.number');
const operatorButton = document.querySelectorAll('.operator');
const clearButton = document.querySelector('.clear');
const deleteButton = document.querySelector('.delete')
const showResult = document.querySelector('.result');
const currentOperand = document.querySelector('.current-operand');
const previousOperand = document.querySelector('.previous-operand');
const equalsKey = document.querySelector('.equals-key');

currentOperand.textContent = ' ';
previousOperand.textContent = ' ';

// Sum of a, b ... 
function add(a, b) {
  return a + b;
};

// Subtraction of a and b ...
function subtract(a, b) {
  return a - b;
};

// Multiply a, b ... 
function multiply(a, b) {
  return a * b;
};

// Divide a,b ... 
function divide(a, b) {
  return a / b;
};

// Create a new function operate that takes an operator and 2 numbers and then calls one of the above functions on the numbers.
function operate(num1, num2, operator) {
  switch (operator) {
    case "+":
      return add(num1, num2);
    case "-":
      return subtract(num1, num2);
    case "*":
      return multiply(num1, num2);
    case "/":
      return divide(num1, num2);
  }
};

//Create the functions that populate the display when you click the 
//number buttons… you should be storing the ‘display value’ in a variable somewhere 
//for use in the next step.

let storedNumber = '';
let clickedOperator = ''
let firstNumber = '';
let result = '';
currentOperand.textContent = 0;


numberButton.forEach((number) => {
  number.addEventListener('click', function() {
    storedNumber += number.value;
    currentOperand.textContent = storedNumber;
  })
});

operatorButton.forEach((operator => {
  operator.addEventListener('click', function() {

    // save the first number
    firstNumber = storedNumber;

    // get the operator that was clicked
    clickedOperator = operator.textContent;
    previousOperand.textContent = storedNumber + clickedOperator;
    storedNumber = '';

    console.log('FirstNumber' + firstNumber + 'Stored' + storedNumber)
    console.log(clickedOperator);

  })
}));

equalsKey.addEventListener('click', function() {
  // when equals key is clicked call operate() function
  result = operate(parseFloat(firstNumber), parseFloat(storedNumber), clickedOperator)
  // update content of current operation with result and previous operand with the calculation, make storedNumber = result
  currentOperand.textContent = result;
  previousOperand.textContent = firstNumber + ' ' + clickedOperator + ' ' + storedNumber;
  storedNumber = result;
  console.log('FirstNumber' + firstNumber + 'Stored' + storedNumber)
})

*,
*::before,
*::after {
  box-sizing: border-box;
  font-weight: normal;
}

body {
  margin: 0;
  padding: 0;
  background: linear-gradient(0.25turn, #3f87a6, #ebf8e1, #f69d3c);
  font-family: sans-serif;
}

.calculator-container {
  display: grid;
  justify-content: center;
  align-content: center;
  min-height: 100vh;
  grid-template-columns: repeat(4, 100px);
  grid-template-rows: minmax(120px, auto) repeat(5, 100px);
}

.two-cols {
  grid-column: span 2;
}

.calculator-container>button {
  cursor: pointer;
  font-size: 2rem;
  border: 1px solid #4289a7;
  outline: none;
  background-color: #f69d3c;
  opacity: 80%;
  border-radius: 5px;
}

.calculator-container>button:hover {
  opacity: 100%;
}

.calculator-display {
  grid-column: 1 / -1;
}

.calculator-display {
  background-color: #efd7a5;
  border: 1px solid #4289a7;
  opacity: 80%;
  display: flex;
  flex-direction: column;
  align-items: flex-end;
  padding: 10px;
  padding-top: 39px;
  padding-bottom: 5px;
  border-radius: 5px;
}

.calculator-display .previous-operand {
  font-size: 1.5rem;
}

.calculator-display .current-operand {
  font-size: 2.5rem;
  padding-top: 7px;
}

!
<!DOCTYPE html>
<!--[if lt IE 7]>      <html class="no-js lt-ie9 lt-ie8 lt-ie7"> <![endif]-->
<!--[if IE 7]>         <html class="no-js lt-ie9 lt-ie8"> <![endif]-->
<!--[if IE 8]>         <html class="no-js lt-ie9"> <![endif]-->
<!--[if gt IE 8]><!-->
<html class="no-js">
<!--<![endif]-->

<head>
  <meta charset="utf-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <title>Calculator Odin Project</title>
  <meta name="description" content="">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <link rel="stylesheet" href="/style.css">
</head>

<body>
  <!--Create a basic HTML calculator with buttons for each digit, each of the above functions and an “Equals” key.
        
            Do not worry about wiring up the JS just yet.
            There should also be a display for the calculator, go ahead and fill it with some dummy numbers so you can get it looking right.
            Add a “clear” button.
        -->

  <div class="calculator-container">
    <div class="calculator-display">
      <div class="previous-operand">3214</div>
      <div class="current-operand">324324</div>
    </div>

    <button class="two-cols clear">AC</button>
    <button class="delete">DEL</button>
    <button class="operator">/</button>
    <button class="number" value="1">1</button>
    <button class="number" value="2">2</button>
    <button class="number" value="3">3</button>
    <button class="operator">*</button>
    <button class="number" value="4">4</button>
    <button class="number" value="5">5</button>
    <button class="number" value="6">6</button>
    <button class="operator">+</button>
    <button class="number" value="7">7</button>
    <button class="number" value="8">8</button>
    <button class="number" value="9">9</button>
    <button class="operator">-</button>
    <button class="number">.</button>
    <button class="number" value="0">0</button>
    <button class="equals-key two-cols result">=</button>

  </div>

  <script src="/index.js" async defer></script>
</body>

</html>


<!--Create a basic HTML calculator with buttons for each digit, each of the above functions and an “Equals” key.

    Do not worry about wiring up the JS just yet.
    There should also be a display for the calculator, go ahead and fill it with some dummy numbers so you can get it looking right.
    Add a “clear” button.
-->

Answer 1

只需运行每次按下数字时的计算，然后更新视图。

例如，如果您按“1”，然后按“+”，然后按“2”，计算器将自动显示“3”。

您还可以让它在单击运算符按钮时计算值，认为它可能没有多大意义。

// DOM elements 
const numberButton = document.querySelectorAll('.number');
const operatorButton = document.querySelectorAll('.operator');
const clearButton = document.querySelector('.clear');
const deleteButton = document.querySelector('.delete')
const showResult = document.querySelector('.result');
const currentOperand = document.querySelector('.current-operand');
const previousOperand = document.querySelector('.previous-operand');
const equalsKey = document.querySelector('.equals-key');

currentOperand.textContent = ' ';
previousOperand.textContent = ' ';

// Sum of a, b ... 
function add(a, b) {
  return a + b;
};

// Subtraction of a and b ...
function subtract(a, b) {
  return a - b;
};

// Multiply a, b ... 
function multiply(a, b) {
  return a * b;
};

// Divide a,b ... 
function divide(a, b) {
  return a / b;
};

// Create a new function operate that takes an operator and 2 numbers and then calls one of the above functions on the numbers.
function operate(num1, num2, operator) {
  switch (operator) {
    case "+":
      return add(num1, num2);
    case "-":
      return subtract(num1, num2);
    case "*":
      return multiply(num1, num2);
    case "/":
      return divide(num1, num2);
  }
};

//Create the functions that populate the display when you click the 
//number buttons… you should be storing the ‘display value’ in a variable somewhere 
//for use in the next step.

let storedNumber = '';
let clickedOperator = ''
let firstNumber = '';
let result = '';
currentOperand.textContent = 0;


numberButton.forEach((number) => {
  number.addEventListener('click', function() {
    storedNumber += number.value;
    previousOperand.textContent += storedNumber;
    calculate();
  })
});

operatorButton.forEach((operator => {
  operator.addEventListener('click', function() {

    // save the first number
    firstNumber = storedNumber;

    // get the operator that was clicked
    clickedOperator = operator.textContent;
    previousOperand.textContent = storedNumber + clickedOperator;
    storedNumber = '';

    console.log('FirstNumber' + firstNumber + 'Stored' + storedNumber)
    console.log(clickedOperator);

  })
}));

const calculate = () => {
  const result = operate(parseFloat(firstNumber), parseFloat(storedNumber), clickedOperator);

  currentOperand.textContent = result;
  }

equalsKey.addEventListener('click', calculate);

*,
*::before,
*::after {
  box-sizing: border-box;
  font-weight: normal;
}

body {
  margin: 0;
  padding: 0;
  background: linear-gradient(0.25turn, #3f87a6, #ebf8e1, #f69d3c);
  font-family: sans-serif;
}

.calculator-container {
  display: grid;
  justify-content: center;
  align-content: center;
  min-height: 100vh;
  grid-template-columns: repeat(4, 100px);
  grid-template-rows: minmax(120px, auto) repeat(5, 100px);
}

.two-cols {
  grid-column: span 2;
}

.calculator-container>button {
  cursor: pointer;
  font-size: 2rem;
  border: 1px solid #4289a7;
  outline: none;
  background-color: #f69d3c;
  opacity: 80%;
  border-radius: 5px;
}

.calculator-container>button:hover {
  opacity: 100%;
}

.calculator-display {
  grid-column: 1 / -1;
}

.calculator-display {
  background-color: #efd7a5;
  border: 1px solid #4289a7;
  opacity: 80%;
  display: flex;
  flex-direction: column;
  align-items: flex-end;
  padding: 10px;
  padding-top: 39px;
  padding-bottom: 5px;
  border-radius: 5px;
}

.calculator-display .previous-operand {
  font-size: 1.5rem;
}

.calculator-display .current-operand {
  font-size: 2.5rem;
  padding-top: 7px;
}

!
<!DOCTYPE html>
<!--[if lt IE 7]>      <html class="no-js lt-ie9 lt-ie8 lt-ie7"> <![endif]-->
<!--[if IE 7]>         <html class="no-js lt-ie9 lt-ie8"> <![endif]-->
<!--[if IE 8]>         <html class="no-js lt-ie9"> <![endif]-->
<!--[if gt IE 8]><!-->
<html class="no-js">
<!--<![endif]-->

<head>
  <meta charset="utf-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <title>Calculator Odin Project</title>
  <meta name="description" content="">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <link rel="stylesheet" href="/style.css">
</head>

<body>
  <!--Create a basic HTML calculator with buttons for each digit, each of the above functions and an “Equals” key.
        
            Do not worry about wiring up the JS just yet.
            There should also be a display for the calculator, go ahead and fill it with some dummy numbers so you can get it looking right.
            Add a “clear” button.
        -->

  <div class="calculator-container">
    <div class="calculator-display">
      <div class="previous-operand">3214</div>
      <div class="current-operand">324324</div>
    </div>

    <button class="two-cols clear">AC</button>
    <button class="delete">DEL</button>
    <button class="operator">/</button>
    <button class="number" value="1">1</button>
    <button class="number" value="2">2</button>
    <button class="number" value="3">3</button>
    <button class="operator">*</button>
    <button class="number" value="4">4</button>
    <button class="number" value="5">5</button>
    <button class="number" value="6">6</button>
    <button class="operator">+</button>
    <button class="number" value="7">7</button>
    <button class="number" value="8">8</button>
    <button class="number" value="9">9</button>
    <button class="operator">-</button>
    <button class="number">.</button>
    <button class="number" value="0">0</button>
    <button class="equals-key two-cols result">=</button>

  </div>

  <script src="/index.js" async defer></script>
</body>

</html>


<!--Create a basic HTML calculator with buttons for each digit, each of the above functions and an “Equals” key.

    Do not worry about wiring up the JS just yet.
    There should also be a display for the calculator, go ahead and fill it with some dummy numbers so you can get it looking right.
    Add a “clear” button.
-->

Answer 2

将计算和显示结果的代码提取到一个单独的函数中。然后您可以从 equals 事件侦听器和所有操作员按钮的事件侦听器调用它。

// DOM elements 
const numberButton = document.querySelectorAll('.number');
const operatorButton = document.querySelectorAll('.operator');
const clearButton = document.querySelector('.clear');
const deleteButton = document.querySelector('.delete')
const showResult = document.querySelector('.result');
const currentOperand = document.querySelector('.current-operand');
const previousOperand = document.querySelector('.previous-operand');
const equalsKey = document.querySelector('.equals-key');

currentOperand.textContent = ' ';
previousOperand.textContent = ' ';

// Sum of a, b ... 
function add(a, b) {
  return a + b;
};

// Subtraction of a and b ...
function subtract(a, b) {
  return a - b;
};

// Multiply a, b ... 
function multiply(a, b) {
  return a * b;
};

// Divide a,b ... 
function divide(a, b) {
  return a / b;
};

// Create a new function operate that takes an operator and 2 numbers and then calls one of the above functions on the numbers.
function operate(num1, num2, operator) {
  switch (operator) {
    case "+":
      return add(num1, num2);
    case "-":
      return subtract(num1, num2);
    case "*":
      return multiply(num1, num2);
    case "/":
      return divide(num1, num2);
  }
};

//Create the functions that populate the display when you click the 
//number buttons… you should be storing the ‘display value’ in a variable somewhere 
//for use in the next step.

let storedNumber = '';
let clickedOperator = ''
let firstNumber = '';
let result = '';
currentOperand.textContent = 0;


numberButton.forEach((number) => {
  number.addEventListener('click', function() {
    storedNumber += number.value;
    currentOperand.textContent = storedNumber;
  })
});

operatorButton.forEach((operator => {
  operator.addEventListener('click', function() {
    if (firstNumber && storedNumber) {
      displayResult();
    }
    // save the first number
    firstNumber = storedNumber;

    // get the operator that was clicked
    clickedOperator = operator.textContent;
    previousOperand.textContent = storedNumber + clickedOperator;
    storedNumber = '';

    console.log('FirstNumber' + firstNumber + 'Stored' + storedNumber)
    console.log(clickedOperator);

  })
}));

equalsKey.addEventListener('click', function() {
  displayResult();
});

function displayResult() {
  result = operate(parseFloat(firstNumber), parseFloat(storedNumber), clickedOperator)
  // update content of current operation with result and previous operand with the calculation, make storedNumber = result
  currentOperand.textContent = result;
  previousOperand.textContent = firstNumber + ' ' + clickedOperator + ' ' + storedNumber;
  storedNumber = result;
  console.log('FirstNumber' + firstNumber + 'Stored' + storedNumber);
}

*,
*::before,
*::after {
  box-sizing: border-box;
  font-weight: normal;
}

body {
  margin: 0;
  padding: 0;
  background: linear-gradient(0.25turn, #3f87a6, #ebf8e1, #f69d3c);
  font-family: sans-serif;
}

.calculator-container {
  display: grid;
  justify-content: center;
  align-content: center;
  min-height: 100vh;
  grid-template-columns: repeat(4, 100px);
  grid-template-rows: minmax(120px, auto) repeat(5, 100px);
}

.two-cols {
  grid-column: span 2;
}

.calculator-container>button {
  cursor: pointer;
  font-size: 2rem;
  border: 1px solid #4289a7;
  outline: none;
  background-color: #f69d3c;
  opacity: 80%;
  border-radius: 5px;
}

.calculator-container>button:hover {
  opacity: 100%;
}

.calculator-display {
  grid-column: 1 / -1;
}

.calculator-display {
  background-color: #efd7a5;
  border: 1px solid #4289a7;
  opacity: 80%;
  display: flex;
  flex-direction: column;
  align-items: flex-end;
  padding: 10px;
  padding-top: 39px;
  padding-bottom: 5px;
  border-radius: 5px;
}

.calculator-display .previous-operand {
  font-size: 1.5rem;
}

.calculator-display .current-operand {
  font-size: 2.5rem;
  padding-top: 7px;
}

!
<!DOCTYPE html>
<!--[if lt IE 7]>      <html class="no-js lt-ie9 lt-ie8 lt-ie7"> <![endif]-->
<!--[if IE 7]>         <html class="no-js lt-ie9 lt-ie8"> <![endif]-->
<!--[if IE 8]>         <html class="no-js lt-ie9"> <![endif]-->
<!--[if gt IE 8]><!-->
<html class="no-js">
<!--<![endif]-->

<head>
  <meta charset="utf-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <title>Calculator Odin Project</title>
  <meta name="description" content="">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <link rel="stylesheet" href="/style.css">
</head>

<body>
  <!--Create a basic HTML calculator with buttons for each digit, each of the above functions and an “Equals” key.
        
            Do not worry about wiring up the JS just yet.
            There should also be a display for the calculator, go ahead and fill it with some dummy numbers so you can get it looking right.
            Add a “clear” button.
        -->

  <div class="calculator-container">
    <div class="calculator-display">
      <div class="previous-operand">3214</div>
      <div class="current-operand">324324</div>
    </div>

    <button class="two-cols clear">AC</button>
    <button class="delete">DEL</button>
    <button class="operator">/</button>
    <button class="number" value="1">1</button>
    <button class="number" value="2">2</button>
    <button class="number" value="3">3</button>
    <button class="operator">*</button>
    <button class="number" value="4">4</button>
    <button class="number" value="5">5</button>
    <button class="number" value="6">6</button>
    <button class="operator">+</button>
    <button class="number" value="7">7</button>
    <button class="number" value="8">8</button>
    <button class="number" value="9">9</button>
    <button class="operator">-</button>
    <button class="number">.</button>
    <button class="number" value="0">0</button>
    <button class="equals-key two-cols result">=</button>

  </div>

  <script src="/index.js" async defer></script>
</body>

</html>


<!--Create a basic HTML calculator with buttons for each digit, each of the above functions and an “Equals” key.

    Do not worry about wiring up the JS just yet.
    There should also be a display for the calculator, go ahead and fill it with some dummy numbers so you can get it looking right.
    Add a “clear” button.
-->

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