Filtering a Table with JavaScript, considering filter in another column using element

Welcome to this tutorial on how to implement table filtering in JavaScript! Filtering table data can greatly enhance the user experience by allowing users to easily find and view specific information. In this tutorial, we will explore how to create a dropdown filter in JavaScript and use it to filter a table based on another column.

When working with large datasets, having the ability to filter and search through the data is essential. In this tutorial, we will show you step by step how to implement a dropdown filter using the <select> element to select a column to filter and filter values from that column.

We will start by creating a table to display our data. We will then add a dropdown menu to select the column we want to filter. When a column is selected, we will dynamically populate the dropdown menu with unique values from that column. Finally, we will add event listeners to the dropdown menu and filter the table based on the selected column and value.

To achieve this, we will use JavaScript to manipulate the DOM and filter the table. We will loop through the table rows, compare the values in the selected column with the selected value, and hide the rows that do not match the filter criterias. The end result will be a fully functional table with a dropdown filter that allows users to easily filter the data based on specific columns and values.

So, let’s get started and learn how to create a dropdown filter for a table in JavaScript!

What is JavaScript Table Filtering?

JavaScript Table Filtering is a technique used to dynamically filter and display specific data in a table based on user input or certain criteria. This allows users to easily search and find the information they want from a large dataset without having to manually scroll or search through the entire table.

The basic concept behind JavaScript Table Filtering is to use JavaScript to manipulate the table’s DOM (Document Object Model) and hide the rows that do not meet the specified criteria. This is commonly done by adding event listeners to filter elements, such as dropdown menus or input fields, and updating the table accordingly based on the selected values or entered text.

One of the commonly used approaches for table filtering is using the <select> element as a dropdown filter. This allows users to select specific values from a predefined list and have the table update accordingly to only display the rows that match the selected value in the filter column.

JavaScript Table Filtering can be beneficial in various scenarios, such as displaying product information, filtering data based on categories, or allowing users to search and sort through large datasets. It provides a dynamic and interactive way to present data in a more organized and user-friendly manner.

Overall, JavaScript Table Filtering is a powerful technique that enhances the usability of a table by allowing users to quickly find specific information. It improves the user experience by reducing the time and effort required to search and filter through a table with large amounts of data.

Why Use Dropdown Filter?

Dropdown filters provide a convenient way to filter table data based on specific criteria. By selecting an option from the dropdown, users can quickly narrow down the displayed content to only the rows that meet their requirements.

This filtering technique is especially useful when dealing with large datasets or complex tables. It allows users to easily find the information they are looking for without scrolling or searching manually. Dropdown filters improve the user experience by reducing the cognitive load and increasing the efficiency of finding relevant data.

Dropdown filters can be implemented in various scenarios, such as e-commerce websites, data analysis tools, or management systems, to name a few. They provide a flexible and intuitive way to interact with tabular data and empower users to customize the view according to their needs.

Overall, the use of dropdown filters can greatly enhance the usability and interactivity of tables. It simplifies the process of locating specific information, saving time and effort for users. When combined with other filtering options, such as text input or checkboxes, dropdown filters offer a versatile solution for organizing and presenting data effectively.

Step-by-Step Guide

  1. Start by creating a table in HTML that you want to filter based on a dropdown filter.
  2. Add a dropdown element ( element, add options (
  3. Add an event listener to the dropdown element to detect when the user selects an option.
  4. In the event listener callback function, get the selected option value.
  5. Loop through each row in the table.
  6. Get the value from the column you want to filter for each row.
  7. If the value matches the selected option value, show the row; otherwise, hide the row.
  8. Repeat Steps 6-8 for all rows in the table.

By following these steps, you can easily implement table filtering with a dropdown filter in your JavaScript application. This allows users to selectively view data based on specific criteria, offering a more streamlined and user-friendly experience.

Step 1: Adding the HTML Table

To start with, we need to add the HTML table to our webpage. This table will be used for demonstrating the functionality of table filtering using a dropdown filter.

Here’s the markup for the HTML table:

<table id="myTable">
<thead>
<tr>
<th>Name</th>
<th>Color</th>
<th>Animal</th>
</tr>
</thead>
<tbody>
<tr>
<td>John</td>
<td>Red</td>
<td>Dog</td>
</tr>
<tr>
<td>Sarah</td>
<td>Blue</td>
<td>Cat</td>
</tr>
<tr>
<td>Michael</td>
<td>Green</td>
<td>Dog</td>
</tr>
<tr>
<td>Emily</td>
<td>Red</td>
<td>Rabbit</td>
</tr>
</tbody>
</table>

The HTML table contains three columns: Name, Color, and Animal. We have added some sample data in the table for demonstration purposes.

Now that we have added the HTML table, we can move on to the next step which is adding the dropdown filter.

Step 2: Creating the Dropdown Filter

Once we have our table data loaded, the next step is to create the dropdown filter. This filter will allow users to select a value from a specific column, and based on that selection, the table will be filtered to display only rows that match the selected value.

To create the dropdown filter, we will need to determine the unique values in the column we want to filter by. We can achieve this by looping through the table data and adding each unique value to an array.

Let’s start by creating a function called createDropdownFilter() that will handle the creation of the dropdown filter:

«`javascript

function createDropdownFilter() {

// Get the unique values from the table column

const columnValues = [];

// Loop through the table rows

for (let i = 1; i < table.rows.length; i++) {

const value = table.rows[i].cells[columnIndex].textContent;

// Check if the value is already in the array

if (!columnValues.includes(value)) {

columnValues.push(value);

}

}

// Sort the values alphabetically

columnValues.sort();

// Create the dropdown element

const dropdown = document.createElement(‘select’);

// Add an option for all values

const optionAll = document.createElement(‘option’);

optionAll.textContent = ‘All’;

dropdown.appendChild(optionAll);

// Add an option for each unique value

for (const value of columnValues) {

const option = document.createElement(‘option’);

option.textContent = value;

dropdown.appendChild(option);

}

// Add an event listener to the dropdown

dropdown.addEventListener(‘change’, filterTable);

// Append the dropdown to the page

const filterContainer = document.getElementById(‘filter-container’);

filterContainer.appendChild(dropdown);

}

In the code above, we start by creating an empty array called columnValues to store the unique values from the table column. We then loop through the table rows, get the value from the desired column for each row, and check if it is already in the columnValues array. If it is not, we add it to the array.

After we have all the unique values, we sort them alphabetically and start creating the dropdown element. We create an option for all values and add it to the dropdown. Then, for each unique value, we create an option and add it to the dropdown as well.

Finally, we add an event listener to the dropdown that will call the filterTable() function whenever the selection changes. We also append the dropdown to the filter-container element on the page.

Now that we have our dropdown filter created, let’s move on to step 3 where we will implement the filterTable() function to filter the table based on the selected value.

Step 3: Writing the JavaScript Function

Now that we have created the necessary HTML markup for our table and dropdown filter, it’s time to write the JavaScript function that will handle the filtering.

First, we need to get references to the HTML elements that we will be working with. We can do this using the getElementById() method.


let filter = document.getElementById('filter');
let table = document.getElementById('table');
let rows = table.getElementsByTagName('tr');

Next, we need to add an event listener to the dropdown filter so that the function is triggered whenever the user selects an option. We can do this using the addEventListener() method.


filter.addEventListener('change', filterTable);

Now let’s write the filterTable() function. This function will be responsible for filtering the table rows based on the selected option in the dropdown filter.


function filterTable() {
let selectedOption = filter.value.toLowerCase();
for (let i = 1; i < rows.length; i++) {
let data = rows[i].getElementsByTagName('td')[1].innerText.toLowerCase();
if (data.indexOf(selectedOption) > -1) {
rows[i].style.display = '';
} else {
rows[i].style.display = 'none';
}
}
}

In the filterTable() function, we first get the value of the selected option in lowercase. Then, we loop through each row of the table starting from index 1, as the first row is the header row.

Inside the loop, we get the text content of the second column (index 1) of each row and convert it to lowercase. We then use the indexOf() method to check if the selected option exists in the data. If it does, we display the row; otherwise, we hide it by setting its display property to ‘none’.

Finally, we need to call the filterTable() function once initially to show all the rows in the table. We can do this by adding the following line of code at the end of our JavaScript function:


filterTable();

That’s it! With the completion of this step, we have successfully written the JavaScript function that filters the table based on the selected option in the dropdown filter.

Example Code

Let’s take a look at an example code snippet that demonstrates how to filter a table based on another column using the <select> element:

 
// Get the table element
const table = document.getElementById("myTable");
// Get the dropdown element
const dropdown = document.getElementById("dropdownFilter");
// Add event listener for dropdown change
dropdown.addEventListener("change", function() {
// Get the selected value from the dropdown
const selectedValue = dropdown.value;
// Loop through each row in the table
Array.from(table.rows).forEach(function(row) {
// Get the cell value from the second column
const cellValue = row.cells[1].innerHTML;
// Check if the cell value matches the selected value
if (selectedValue === "All"

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