Utilizing the Onchange Event with Multiple Input Fields in Vanilla JavaScript

Question

Utilizing the Onchange Event with Multiple Input Fields in Vanilla JavaScript

I'm working on a website where multiple inputs need to be created dynamically using createElement. Each input can have its own class, id, and other attributes.

The main objective is to automatically calculate the overall price whenever a user adds a new input (such as the amount of products). This should be done without requiring any additional clicks, with the calculation being based on the product price multiplied by the quantity entered in the input field.

While I could share the code, I believe an image would better illustrate the concept. You can view it here: https://i.stack.imgur.com/c33KZ.png

I am looking for guidance on how to implement this functionality using onchange with getElementByTagName. An example would be greatly appreciated. Thank you!

javascript object events onchange

Answer 1

Answer №1

To optimize your event handling, consider using event delegation. By focusing on a common ancestor element where events will bubble up to from child elements, you can reduce the number of listeners needed. I recommend listening for the "input" event which captures any changes made by the user:

document.addEventListener("input", function() {
    // perform calculations here:
});

This approach allows you to simplify your code by attaching just one listener.

Answer 2

To optimize your event handling, consider using event delegation. By focusing on a common ancestor element where events will bubble up to from child elements, you can reduce the number of listeners needed. I recommend listening for the "input" event which captures any changes made by the user:

document.addEventListener("input", function() {
    // perform calculations here:
});

This approach allows you to simplify your code by attaching just one listener.

Answer 3

Answer №2

Here is an example of how you can achieve this:

function updateValue() {
  // Update value function
}
const allInputs = [...document.getElementsByTagName('input')];
allInputs.forEach(input => input.addEventListener('click', updateValue));

Answer 4

Here is an example of how you can achieve this:

function updateValue() {
  // Update value function
}
const allInputs = [...document.getElementsByTagName('input')];
allInputs.forEach(input => input.addEventListener('click', updateValue));

Answer 5

Answer №3

Using classes is a more efficient way to handle inputs, rather than applying the same function to all of them. If you're looking for an example, here's something that might help:

function addInputListener(input) {
    //@todo Replace this with your own data
    let row = input.parentElement.parentElement;
    let overallPriceElement = row.querySelector('.overall-price');
    let price = parseInt(row.querySelector('.price').innerText);
    let calcEvent = function() {
        //@todo Enter your calculation function here
        if (this.value > 0) {
            overallPriceElement.innerText = (price * this.value).toString();
        } else {
            overallPriceElement.innerText = "No products yet";
        }
    };

    input.addEventListener('input', calcEvent);
    calcEvent.call(input); // call() used to add input context
}

// Using a class is preferred over a tag for functionality
let inputs = document.querySelectorAll('.amount');

for (let i = 0; i < inputs.length; i++) {
    let input = inputs[i];
    addInputListener(input);
}

<table>
    <thead>
    <tr>
        <th>#</th>
        <th>Name</th>
        <th>Price</th>
        <th>Amount</th>
        <th>Overall Price</th>
    </tr>
    </thead>
    <tbody>
    <tr>
        <td>1</td>
        <td>Bread</td>
        <td class="price">3</td>
        <td><input type="number" class="amount"></td>
        <td class="overall-price"></td>
    </tr>
    <tr>
        <td>2</td>
        <td>Bread</td>
        <td class="price">10</td>
        <td><input type="number" class="amount"></td>
        <td class="overall-price"></td>
    </tr>
    <tr>
        <td>3</td>
        <td>Bread</td>
        <td class="price">30</td>
        <td><input type="number" class="amount"></td>
        <td class="overall-price"></td>
    </tr>
    </tbody>
</table>

To apply the addInputListener(input) function each time you create a new row, simply pass the newly created input using createElement to these listeners.

Answer 6

Using classes is a more efficient way to handle inputs, rather than applying the same function to all of them. If you're looking for an example, here's something that might help:

function addInputListener(input) {
    //@todo Replace this with your own data
    let row = input.parentElement.parentElement;
    let overallPriceElement = row.querySelector('.overall-price');
    let price = parseInt(row.querySelector('.price').innerText);
    let calcEvent = function() {
        //@todo Enter your calculation function here
        if (this.value > 0) {
            overallPriceElement.innerText = (price * this.value).toString();
        } else {
            overallPriceElement.innerText = "No products yet";
        }
    };

    input.addEventListener('input', calcEvent);
    calcEvent.call(input); // call() used to add input context
}

// Using a class is preferred over a tag for functionality
let inputs = document.querySelectorAll('.amount');

for (let i = 0; i < inputs.length; i++) {
    let input = inputs[i];
    addInputListener(input);
}

<table>
    <thead>
    <tr>
        <th>#</th>
        <th>Name</th>
        <th>Price</th>
        <th>Amount</th>
        <th>Overall Price</th>
    </tr>
    </thead>
    <tbody>
    <tr>
        <td>1</td>
        <td>Bread</td>
        <td class="price">3</td>
        <td><input type="number" class="amount"></td>
        <td class="overall-price"></td>
    </tr>
    <tr>
        <td>2</td>
        <td>Bread</td>
        <td class="price">10</td>
        <td><input type="number" class="amount"></td>
        <td class="overall-price"></td>
    </tr>
    <tr>
        <td>3</td>
        <td>Bread</td>
        <td class="price">30</td>
        <td><input type="number" class="amount"></td>
        <td class="overall-price"></td>
    </tr>
    </tbody>
</table>

To apply the addInputListener(input) function each time you create a new row, simply pass the newly created input using createElement to these listeners.

Utilizing the Onchange Event with Multiple Input Fields in Vanilla JavaScript

Answer №1

Answer №2

Answer №3

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