How to find the first line of the each page in pdf? is this possible to find the new line using javascript(/n or /r)

You can retrieve the text in a PDF using JavaScript, but determining what is the first line is not so trivial.

First of all you'll need to define what is the "first line" of a page. Does it include header? Titles? What if the page has multiple columns? etc. On top of that the order in which the script returns the words in the page does not necessarily correspond to their physical order, so you would need to sort them first. And on top of that, each word is returned on its own, and there may or may not be line-breaks in them, so you would need to analyze their locations and determine which ones are on the same line...