In Node.js, given a URL, how do I check whether its a jpg/png/gif?
Just read the first bytes of the stream, and check it for the so called "magic number".
Magic numbers are the first bits of a file which uniquely identify thetype of file.
For example:
-Every JPEG file begins with ff d8 (hex).
-Every png file begins with a 89 50 4e 47.
-There is a comprehensive table of magic numbers here
This way even if you have a file without extension you can still detect its type.
Hope this helps.
This code shows a working solution for the magic numbers approach (summary of the existing answers and information on https://github.com/request/request).
var request = require('request');var url = "http://www.somedomain.com/somepicture.jpg";var magic = { jpg: 'ffd8ffe0', png: '89504e47', gif: '47494638'};var options = { method: 'GET', url: url, encoding: null // keeps the body as buffer};request(options, function (err, response, body) { if(!err && response.statusCode == 200){ var magigNumberInBody = body.toString('hex',0,4); if (magigNumberInBody == magic.jpg || magigNumberInBody == magic.png || magigNumberInBody == magic.gif) { // do something } }});