React JS Upload Image when user pastes an Image

September 9, 2022

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.

>Solution :

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 item.type.indexOf('image') !== -1;
                    });
                    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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