嗨，我是一个新的程序员，我正在使用免费代码夏令营学习js.我目前正在进行卡路里计数练习，我正在复制VsCode中的代码.我刚刚使用查询 Select 器向js添加了一个addEntry按钮，并收到以下错误:
未捕获的TypeError TypeErpeError:无法读取Null的属性(正在读取 ‘querySelectorAll’) 在addEntry-Filepath卡路里计数器.js 21
我是个彻头彻尾的新手，我不知道该找什么.
Index.html:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8" />
<meta name="viewport" content="device=device-width, initial-scale= 1.0" />\
<link rel="stylesheet" href="C:\Users\babat\OneDrive\Desktop\Vs Code Projects\JsApps\Calorie Counter.css" />
<title>Calorie Counter</title>
</head>
<body>
<main>
<h1>Calorie Counter</h1>
<div class="container">
<form id="calorie-counter">
<label for="budget">Budget</label>
<input id="budget" type="number" min="0" placeholder="Daily Calorie Counter" required />
<fieldset class="breakfast">
<legend>Breakfast</legend>
<div class="input-container"></div>
</fieldset>
<fieldset id="lunch">
<legend>Lunch</legend>
<div class="input-container"></div>
</fieldset>
<fieldset id="dinner">
<legend>Dinner</legend>
<div class="input-container"></div>
</fieldset>
<fieldset id="snacks">
<legend>Snacks</legend>
<div class="input-container"></div>
</fieldset>
<fieldset id="exercise">
<legend>Exercise</legend>
<div class="input-container"></div>
</fieldset>
<div class="controls">
<span>
<label for="entry-dropdown">Add food or exercise</label>
<select id="entry-dropdown" name="options">
<option value="breakfast" selected>Breakfast</option>
<option value="lunch">Lunch</option>
<option value="dinner">Dinner</option>
<option value="snacks">Snacks</option>
<option value="exercise">Exercise</option>
</select>
<button id="add-entry" type="button">Add Entry</button>
</span>
</div>
<div>
<button type="submit">Calculate Remaining Calories</button>
<button id="clear" type="button">Clear</button>
</div>
</form>
<div id="output" class="output hide"></div>
</div>
</main>
<script src="C:\Users\babat\OneDrive\Desktop\Vs Code Projects\JsApps\Calorie Counter.js"></script>
</body>
</html>
另请参阅以下内容:
:root {
--light-grey: #f5f6f7;
--dark-blue: #0a0a23;
--fcc-blue: #1b1b32;
--light-yellow: #fecc4c;
--dark-yellow: #feac32;
--light-pink: #ffadad;
--dark-red: #850000;
--light-green: #acd157;
}
body {
font-family: "Lato", Helvetica, Arial, sans-serif;
font-size: 18px;
background-color: var(--fcc-blue);
color: var(--light-grey);
}
h1 {
text-align: center;
}
.container {
width: 90%;
max-width: 680px;
}
h1,
.container,
.output {
margin: 20px auto;
}
label,
legend {
font-weight: bold;
}
.input-container {
display: flex;
flex-direction: column;
}
button {
outline: none;
cursor: pointer;
text-decoration: none;
background-color: var(--light-yellow);
border: 2px solid var(--dark-yellow);
}
.clear {
background-color: var(--light-pink);
color: var(--dark-red);
border-color: var(--dark-red);
}
button,
input,
select {
min-height: 24px;
color: var(--dark-blue);
}
fieldset,
label,
button,
input,
select {
margin-bottom: 10px;
}
.output {
border: 2px solid var(--light-grey);
padding: 10px;
text-align: center;
}
.hide {
display: none;
}
.output span {
font-weight: bold;
font-size: 1.2em;
}
.surplus {
color: var(--light-green);
}
.deficit {
color: var(--light-pink);
}
Java:
const calorieCounter = document.getElementById('calorie-counter');
const budgetNumberInput = document.getElementById('budget');
const entryDropdown = document.getElementById('entry-dropdown');
const addEntryButton = document.getElementById('add-entry');
const clearButton = document.getElementById('clear');
const output = document.getElementById('output');
let isError = false;
function cleanInputString(str) {
const regex = /[+-\s]/g;
return str.replace(regex, '');
}
function isInvalidInput(str) {
const regex = /\d+e\d+/i;
return str.match(regex);
}
function addEntry() {
const targetInputContainer = document.querySelector(`#${entryDropdown.value} .input-container`);
const entryNumber = targetInputContainer.querySelectorAll('input[type="text"]').length + 1;
const HTMLString = `
<label for="${entryDropdown.value}-${entryNumber}-name">Entry ${entryNumber} Name</label>
<input type="text" id="${entryDropdown.value}-${entryNumber}-name" placeholder="Name" />
<label for="${entryDropdown.value}-${entryNumber}-calories">Entry ${entryNumber} Calories</label>
<input
type="number"
min="0"
id="${entryDropdown.value}-${entryNumber}-calories"
placeholder="Calories"
/>`;
targetInputContainer.insertAdjacentHTML('beforeend', HTMLString);
}
addEntryButton.addEventListener("click", addEntry);
代码在freecode Camp应用程序的预览窗口中可以运行，但当我在Visual Studio代码中运行它时，它不能运行，并抛出错误.我try 将应用程序中的代码直接复制并粘贴到VS代码中，但仍然收到错误.