curriculum/challenges/english/blocks/learn-form-validation-by-building-a-calorie-counter/63c9bcc26219e7090da0f549.md
In programming, null is meant to represent the absence of a value. In this case, if the user enters an invalid input, you want to alert them and then return null to indicate that the function has failed.
Still within your if block, set isError to true and return null.
After your alert, you should set isError to true.
assert.match(code.split(/function\s+getCaloriesFromInputs/)[1], /(?:window\.|globalThis\.)?alert\(\s*`Invalid Input: \${invalidInputMatch\s*\[\s*0\s*\]\s*}`\s*\)\s*;?\s*isError\s*=\s*true/);
After you modify isError, you should return the value null.
assert.match(code.split(/function\s+getCaloriesFromInputs/)[1], /(?:window\.|globalThis\.)?alert\(\s*`Invalid Input: \${invalidInputMatch\s*\[\s*0\s*\]\s*}`\s*\)\s*;?\s*isError\s*=\s*true\s*;?\s*return\s+null\s*;?\s*\}/);
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<link rel="stylesheet" href="styles.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
type="number"
min="0"
id="budget"
placeholder="Daily calorie budget"
required
/>
<fieldset id="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 type="button" id="add-entry">Add Entry</button>
</span>
</div>
<div>
<button type="submit">
Calculate Remaining Calories
</button>
<button type="button" id="clear">Clear</button>
</div>
</form>
<div id="output" class="output hide"></div>
</div>
</main>
<script src="./script.js"></script>
</body>
</html>
: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 {
cursor: pointer;
text-decoration: none;
background-color: var(--light-yellow);
border: 2px solid var(--dark-yellow);
}
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-pink);
}
.deficit {
color: var(--light-green);
}
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);
}
--fcc-editable-region--
function getCaloriesFromInputs(list) {
let calories = 0;
for (const item of list) {
const currVal = cleanInputString(item.value);
const invalidInputMatch = isInvalidInput(currVal);
if (invalidInputMatch) {
alert(`Invalid Input: ${invalidInputMatch[0]}`);
}
}
}
--fcc-editable-region--
addEntryButton.addEventListener("click", addEntry);