how get image md5 hash in the browser from image buffer in javascript

To get an image's MD5 hash in the browser from an image buffer in JavaScript, you can use the crypto.subtle.digest() method.

First, you need to convert the image buffer to an ArrayBuffer, which can be done using the FileReader API. Then, you can use the crypto.subtle.digest() method to generate an MD5 hash of the ArrayBuffer.

Here's an example code block that demonstrates this process:

index.tsx
function getMD5HashFromImageBuffer(buffer) {
  return new Promise((resolve, reject) => {
    const fileReader = new FileReader();
    fileReader.onload = () => {
      const arrayBuffer = fileReader.result;
      crypto.subtle.digest("MD5", arrayBuffer).then(hash => {
        resolve(hash);
      }).catch(error => {
        reject(error);
      });
    };
    fileReader.readAsArrayBuffer(buffer);
  });
}

// Example usage:
const imageBuffer = new Uint8Array([137, 80, 78, 71, 13, 10, 26, 10, 0, 0, 0, 13, 73, 72, 68, 82]).buffer;
getMD5HashFromImageBuffer(imageBuffer).then(hash => {
  const hexString = Array.from(new Uint8Array(hash)).map(b => b.toString(16).padStart(2, '0')).join('');
  console.log(`MD5 hash of image buffer: ${hexString}`);
}).catch(error => {
  console.error(error);
});
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In this example, we define a getMD5HashFromImageBuffer() function that takes an image buffer as input and returns a Promise that resolves with the MD5 hash of the image buffer. We use the FileReader API to convert the buffer to an ArrayBuffer, and then use the crypto.subtle.digest() method to generate an MD5 hash of the ArrayBuffer. Finally, we convert the hash to a hex string and log it to the console.

To use this function, you would call it with an image buffer (in this example, we create a test buffer with the PNG header). The function returns a Promise that resolves with the hash, which you can then use as needed.