Puppeteer: change URL of intercepted image request to a base64 image

Question

I need to intercept .jpg and .gif images and replace them with a base64 image instead. The base64 images would then be visible in the screenshot.

The below code prevents the original image from loading, but the base64 image is not loaded in the place of the original images.

How can I replace the original image's src with the base64 image?

await page.setRequestInterception(true);

page.on('request', request => {

const resourceUrl = request.url().toLowerCase();
const base64Image = 'data:image/png;base64,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';

if (request.resourceType() == 'image' && resourceUrl.indexOf('.png') === -1 && 
    resourceUrl.indexOf('.svg') === -1 ||
    resourceUrl.indexOf('.jpg') !== -1 ||
    resourceUrl.indexOf('.jpeg') !== -1 ||
    resourceUrl.indexOf('.gif') !== -1) {

        request.respond({
            status: 200,
            contentType: 'image/jpeg',
            headers: {
            // location: base64Image
            // path: base64Image
            url: base64Image
          },
        });

       return; // prevent calling continue twice

}

request.continue();

});

Answer 1

Problem

request.respond cannot be used with base64 reponses. Quote from the docs:

NOTE Mocking responses for dataURL requests is not supported.

Solution

Instead, you can answer with the buffered data which you need to convert from base64 to its binary representation first:

const base64Data = 'iVBORw0KGgoAAA...'; // ony the base64 data, without "data:image/png;base64,"
const buffer = Buffer.from(base64Data, 'base64');

// ...

request.respond({
    status: 200,
    contentType: 'image/png',
    body: buffer
});