wtf is resumable.js?

Resumable.js is a JavaScript library that makes uploading large files through a website more reliable. Instead of sending an entire file in one go, it breaks files into small pieces and sends them individually. If a network connection drops, only the failed pieces need to be retried, not the whole file. Users can also pause and resume uploads without losing progress. The tool works by splitting each file into chunks and uploading a few at a time. The browser sends each chunk to the server along with details like its position in the file, the total number of chunks, and a unique identifier for the file. The server's job is to receive these chunks and reassemble them into the complete file. If a chunk fails to upload, the library automatically retries it. An optional feature lets the browser check which chunks the server already has, so uploads can resume even after a browser restart or a computer crash. This library would be used by developers building web applications where users upload large files, such as video sharing platforms, cloud storage services, or photo hosting sites. For example, a video creator uploading a 2GB file over a spotty connection could pause, switch networks, and resume without starting over. A photographer uploading a folder of high-resolution images could benefit from the simultaneous upload feature, which sends multiple chunks at once to speed up the process. A notable design choice is that the library has no external dependencies beyond standard browser capabilities. It relies on the HTML5 File API, which is supported in modern browsers including Firefox, Chrome, Safari, and Internet Explorer 10 and above. The library also provides extensive configuration options, letting developers control chunk size, the number of simultaneous uploads, file type and size limits, and how the server should respond to successful and failed uploads.