What is best way to compress file and text "inside browser" before sending to server?

Actually I trying to upload large text and pdf files. I want to compress file chunks in browser only. So i can encrypt and send these lite chunk through ajax smoothly without hanging browser. I am seeking help related to file chunk compression. And at server side easily can decompress using java library. Can anyone suggest me best way to do it ? It should be in client side and inside browser(IE11,Google Chrome).