This is the worst website, because the image quality is low and worst explanation. In w3schools they have nice and simple example.
1) Tutorial point is copied w3schools.com website contents and expand the it and published.
2) Lots of advertisement, so their main aim is not to teaching people, only they focus for their earning.
3) Many contents, they not only focus the programming area.
4) Fully of copy write content, just take a look in ionic tutorial, full of copied from(https://only4programmers.blogspot.in/2016/10/ionic.html) this website