जो समय समय पर सामग्री में परिवर्तन के लिए वेब पृष्ठों की जाँच करता है कोई एप्लिकेशन

Check Page is an app which periodically checks Web pages for content changes. It is targeted at advanced Web users, who are able to read HTML code and write a Xpath or CSS query to extract the data of interest.

CSS queries allows you to select data by HTML tag names, ids, classes and more:

- h1(selects <h1>)

- #computers(selects elements with id="computers")

- span.title(selects <span class="computers">)

More info: https://developer.mozilla.org/en-US/docs/Learn/CSS/Introduction_to_CSS/Selectors

Xpath queries are slightly more complex, but allows more control on what data is being selected and provides functions to transform that data:

- //h1[2](selects second <h1> element in the page)

- //*[@id='computers'](selects any element with id="computers")

- //span[@class]/@class(selects class attribute values of <span> elements)

- //li/substring-before(., ',')(selects <li> elements and returns inner text before first comma)

More info: https://www.w3schools.com/xml/xpath_intro.asp

FAQ:

Q: I've selected update period of X minutes, but sometimes the period between two consecutive updates is much longer. Why is that?

A: The updates are scheduler by Android OS. In order to reduce battery consumption Android schedules some actions to be run more or less often than requested.