How to build a JavaScript-based recipe app with a dynamic ingredient calculator?
13/03/2024
•
5
min
Building a recipe app with a dynamic ingredient calculator involves several steps: setting up your environment, designing your user interface, setting up your recipe form and ingredients calculator, and finally incorporating your JavaScript to pull it all together.
The app will work by users entering the quantity they want for a particular recipe, then the ingredient calculator will dynamically adjust based on that input.
Let's get started.
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Step 1: Setup your environment:
- A basic text editor (VS Code, Sublime Text, or Atom).
- A modern web browser for testing (Google Chrome, Mozilla Firefox).
Step 2: Design the User Interface:
We'll need a form where users can enter the number of servings they want, a place to display the recipe, and an area where the adjusted ingredients will be displayed.
Create a new HTML file and start by setting up a basic HTML boilerplate.
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Recipe Calculator</title>
</head>
<body>
</body>
</html>
Step 3: Setup the Recipe form and Ingredients calculator:
Next, we'll add our form inside the body tag. This form will contain an input field for the serving size, and a button to submit the form.
<body>
<form id="servingForm">
<label for="servings">Enter number of servings: </label>
<input type="number" id="servings" min="1" step="1">
<button type="submit">Submit</button>
</form>
</body>
Then, we'll add a section to display the recipe. This will include the name of the recipe and a list of ingredients with their quantities. Here, we'll use a <ul> to display the list of ingredients.
<body>
<!-- Serving Form -->
...
<div>
<h2 id="recipeName">Recipe Name</h2>
<ul id="ingredientList">
<li>1 cup of Flour</li>
<li>2 Eggs</li>
<li>1/2 cup of Sugar</li>
</ul>
</div>
</body>
Finally, we'll add a div to display the calculated ingredient values.
<body>
<!-- Serving Form -->
...
<!-- Recipe -->
...
<div>
<h2>Ingredients for Your Serving</h2>
<ul id="calculatedIngredientsList">
</ul>
</div>
</body>
Step 4: Build the Ingredients Calculator:
To make our calculator work, we'll need to write a JavaScript function that takes the serving size, and the list of ingredients, then returns a new list of ingredients scaled by the serving size.
First, include a new JavaScript file in your HTML. Add this right before the body tag ends.
<script src="app.js"></script>
Now, create this 'app.js' file and add the following functionality:
document.getElementById('servingForm').addEventListener('submit', function(e) {
// Prevent the form from submitting normally
e.preventDefault();
// Get the number of servings from the user input
var servings = document.getElementById('servings').value;
// Get all the ingredients from the ingredient list
var ingredients = document.getElementById('ingredientList').getElementsByTagName('li');
// Get the calculated ingredients list
var calculatedIngredientsList = document.getElementById('calculatedIngredientsList');
// Clear the calculated ingredients list
calculatedIngredientsList.innerHTML = '';
// Loop through each ingredient
for(var i = 0; i < ingredients.length; i++) {
// Split the ingredient into quantity and item
var ingredientParts = ingredients[i].innerText.split(' ');
// Get the quantity and convert it to a number
var quantity = Number(ingredientParts.shift());
// Update the quantity based on the number of servings
quantity *= servings;
// Add the updated ingredient to the calculated ingredients list
calculatedIngredientsList.innerHTML += '<li>' + quantity + ' ' + ingredientParts.join(' ') + '</li>';
}
});
Whenever the serving form is submitted, this function will trigger. It gets the serving size, and each ingredient, then calculates the new ingredient quantities based on the serving size. It then displays this updated ingredient list in the 'calculatedIngredientsList' div.
Remember to check for arising bugs and browser compatibility issues. It's also recommended to further refine the calculator to handle more complex recipes and ingredient units. Moreover, you can use a JavaScript framework or library such as React or Vue.js to make your work easier.
Finally, this is a basic example and might not suffice for professional use-cases. But this should help you understand the basis of how to build a JavaScript-based recipe app with an ingredient calculator.
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