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Have you ever wondered how to use JavaScript to open a file input dialog by clicking a button? This is a common question that comes up for developers, especially when creating user-friendly interfaces that require file uploads. In this article, we’ll examine a simple solution to this problem, involving the HTML ‘input’ element, some CSS, and a little bit of JavaScript magic.
We’ll guide you through the code, explain why it works, and point out the important facets to remember for your future coding endeavors.
Unearthing the Problem
Firstly, let’s understand the problem more thoroughly. The ‘input’ type ‘file’ in HTML creates a simple file input field in the browser. The problem, however, is that the appearance and functionality of this field might not always meet the UX needs of your application.
[class lang=”JavaScript”][/class]
Some older browsers do not support file uploads, and others make the ‘browse’ button expand way beyond the field itself. This makes it hard to style. So what can be done? This article implements a solution with a specific button to achieve this goal.
A JavaScript Solution
Our solution involves hiding the original ‘browse’ button and creating a new one, which when clicked, triggers the hidden file input dialog.
To do this, we can use the ‘click’ event in JavaScript.
//HTML
<ul>
<li><input id="fileInput" type="file" style="display: none;" /></li>
<li><button onclick="openInputFile()">Open Input File</button></li>
</ul>
//JavaScript
function openInputFile(){
document.getElementById('fileInput').click();
}
After selecting the file, you can fetch the file data with JavaScript by accessing the ‘files’ property of the file input:
let fileInput = document.getElementById('fileInput');
let file = fileInput.files[0];
Libraries To Enhance Functionality
If you’d like to go a step further and work with file processing libraries, FileReader API is a great place to start. With this API, you can read the contents of files (or raw data buffers) stored on the user’s computer.
let reader = new FileReader();
reader.onload = function(e){
console.log(e.target.result);
}
reader.readAsText(file);
Similar Functions and Further Readings
For further learning, you can explore File API and FormData objects. File API provides information about files and allows JavaScript in a web browser to access their content while FormData is used to construct a set of key/value pairs to send using XMLHttpRequest.
Overall, as a JavaScript developer, mastering the manipulation of files in the browser can be a useful skill, enabling you to build interactive, user-friendly forms and applications.
