Scraping articles on a web site
As for the jQuery/function usage, there is definitely room for improvement but it would be helpful to see an example HTML element that contains the article img, title, and url to understand the page structure a bit.
I think your variable names are clear, but could be simplified. Also, it is common practice to use Camel Case with the first letter lowercase for Node/Javascript instead of underscores between words.


For example, replace number_of_articles_beforehand with numArticlesBefore

Here is an article I found helpful regarding var, let, const 


https://medium.com/javascript-scene/javascript-es6-var-let-or-const-ba58b8dcde75
Javascript allows variable hoisting (click here for more info) with the keyword var whereas variables/identifiers declared as let or const do not hoist.
Personally, I have stopped using var altogether to help improve code readability as mentioned in the article above. Also, it is common practice to use const for the Node package require statements instead of var.
Remove the var title, url, image; line because you are only using those variables within their respective functions.
Lastly, I would encourage you to replace i = i + 1; with i++;. It does the same thing and is easier to read. (FYI, i--; would decrement i by 1).