How to Implement Client-Side Image Preview Before Upload?

Showcasing Image Previews Before Uploading

Previewing images before uploading them enhances the user experience by granting users a glimpse of the content they intend to share. Executing this preview entirely within the browser, eliminating the need for Ajax requests, ensures a seamless and efficient process.

Implementing Image Preview Capabilities

To achieve image preview functionality, harness the capabilities of the FileReader API and URL.createObjectURL() method. This approach allows you to load the selected image file as a URL and display it within an image element, as demonstrated below:

imgInp.onchange = evt => {
  const [file] = imgInp.files;
  if (file) {
    blah.src = URL.createObjectURL(file);
  }
};

<form runat="server">
  <input accept="image/*" type='file'>

This code captures the image file from the input field (imgInp) and constructs a URL that represents the image's content using URL.createObjectURL(file). Subsequently, the image element (blah) is assigned this URL, displaying the selected image as a preview.

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