如何将缓冲区转换为 pdf/docx

Question

        await newPage.setRequestInterception(true);
        const xRequest = await new Promise(resolve => {
            newPage.on('request', interceptedRequest => {
                interceptedRequest.abort();     //stop intercepting requests
                resolve(interceptedRequest);
            });
        });

        const options = {
            encoding: null,
            method: xRequest._method,
            uri: xRequest._url,
            body: xRequest._postData,
            headers: xRequest._headers
        }
        
        const cookies = await newPage.cookies();
        options.headers.Cookie = cookies.map(ck => ck.name + '=' + ck.value).join(';');
        
        const res = await request(options);

I'm using puppeteer and trying to download some pdf/docx and getting res as buffer. How can I check the file type from buffer (res) and convert it to that particular file type.

Answer 1

if you have the buffer in your hands you dont need to "convert" it. you can for exemple write it to a file and you will be able to open it with your explorer for example.

fs.writeFile('filename.pdf', buffer);

Also, the solution to your question already exist here: Detecting file type from buffer in node js? please take time to find already existing solutions on stack overflow before posting.

a buffer contains a pdf if the first bytes are [0x25, 0x50, 0x44, 0x46] you can simply test it like this:

var isPdf = (buffer[0] == 0x25 && buffer[1] == 0x50 && buffer[2] == 0x44 && buffer[3] == 0x46);