Show Image Preview using jQuery

5 mins0
Show image preview using jQuery

When users upload images, it’s helpful to let them see a preview before sending it to the server. This way, they can quickly spot mistakes and remove or change any wrong images. You can implement this seamlessly with jQuery. In this tutorial, we will show how to show image preview using jQuery with a simple example where users select an image and instantly see it on the page.

First of all, let’s define basic markup for our web page then we will add our code for showing image preview. Here, you can use the existing code or copy the below code.

<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="utf-8">
        <title>ImagePreview Using JavaScript</title>
    </head>
    <body>
        <input id="image" type="file" name="image">

        <div id="imageDisplay"> </div>
        <script src="https://code.jquery.com/jquery-3.6.0.min.js" integrity="sha256-/xUj+3OJU5yExlq6GSYGSHk7tPXikynS7ogEvDej/m4=" crossorigin="anonymous"></script>
    </body>
</html>

Here, we just added a simple input field with file type and assigned an ID to it. Also, defined HTML div element which is used to show image preview to the user.

We will use the FileReader object to show an image preview. The FileReader lets web applications read the contents of users’ files asynchronously. By using File or Blob objects to specify the file or data to read, your program continues running without stalling while processing large files. This method works well for handling big files efficiently.

Following is a code sample to create a new instance of FileReader.

var fr = new FileReader();

Here, we have bound input with a change event and applied our logic to that function. The change event will be triggered when the user selects an image file. Let’s take an example to create our functionality. Add the below code at the end of the body tag.

$("#image").on('change', function () {
    var fr = new FileReader();
    if (typeof (FileReader) != "undefined") {

        var imageDisplay = $("#imageDisplay");
        imageDisplay.empty();

        var reader = new FileReader();
        reader.onload = function (e) {
            $("", {
                "src": e.target.result,
                "class": "thumb-image"
            }).appendTo(imageDisplay);
        }
        reader.readAsDataURL($(this)[0].files[0]);
    } else {
        alert("Your browser does not support FileReader.");
    }
});

In the above code, first of all, we have defined on change event, and when on change event triggers it will create a new instance of FileReader. Then empty image displays div. At last, it will create a new image element and append it to the image display image.

Conclusion

In this article, we have taken a simple example to show an image preview to a user using jQuery and FileReader-based logic. There are many ready to use a library to perform this task easily.

We just covered how to show an image preview using jQuery. For handling video files and letting users preview them before upload, check out our guide on Show Video Preview using JavaScript.

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