I am developing a chat application on React JS, and I want an image to be uploaded if I copy paste an image on the chatbox. How do I trigger this? What I need basically is: An event that will be triggered when action "Paste" is performed. A way to upload image into a file type input element from the

React JS Upload Image when user pastes an Image

I am developing a chat application on React JS, and I want an image to be uploaded if I copy paste an image on the chatbox. How do I trigger this?

What I need basically is:

An event that will be triggered when action “Paste” is performed.
A way to upload image into a file type input element from the clipboard.

Answer

You need to add an event listener on paste event, and get the items from the clipboard and check if its type is an image.

<html lang="en">
    <head>
        <meta charset="utf-8" />
        <title>HTML DOM - Paste an image from the clipboard</title>
        <meta name="viewport" content="width=device-width, initial-scale=1" />
        <link rel="stylesheet" href="/css/demo.css" />
        <link rel="preconnect" href="https://fonts.gstatic.com" />
        <link
            rel="stylesheet"
            href="https://fonts.googleapis.com/css2?family=Inter&family=Source+Code+Pro&display=swap"
        />
        <style>
            .container {
                /* Center the content */
                align-items: center;
                display: flex;
                justify-content: center;

                /* Misc */
                height: 32rem;
                padding: 1rem 0;
            }
            .key {
                background-color: #f7fafc;
                border: 1px solid #cbd5e0;
                border-radius: 0.25rem;
                padding: 0.25rem;
            }
            .preview {
                align-items: center;
                border: 1px solid #cbd5e0;
                display: flex;
                justify-content: center;

                margin-top: 1rem;
                max-height: 16rem;
                max-width: 42rem;
            }
        </style>
    </head>
    <body>
        <div class="container">
            <div>
                <div><kbd class="key">Ctrl</kbd> + <kbd class="key">V</kbd> in this window.</div>
                <img class="preview" id="preview" />
                <input id="file_input" type="file" />
            </div>
        </div>
       
        <script>
            document.addEventListener('DOMContentLoaded', function () {
                document.addEventListener('paste', function (evt) {
                    const clipboardItems = evt.clipboardData.items;
                    const items = [].slice.call(clipboardItems).filter(function (item) {
                        // Filter the image items only
                        return /^image//.test(item.type);
                    });
                    if (items.length === 0) {
                        return;
                    }

                    const item = items[0];
                    const blob = item.getAsFile();

                    const imageEle = document.getElementById('preview');
                    imageEle.src = URL.createObjectURL(blob);
                    let file = new File([blob], "file name",{type:"image/jpeg", lastModified:new Date().getTime()}, 'utf-8');
                    let container = new DataTransfer(); 
                    container.items.add(file);
                    document.querySelector('#file_input').files = container.files;
                });
            });
        </script>
    </body>
</html>

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