Javascript tips and tricks

This ==>

The object that is executing the current function

method-obj

function => global window

construction 

const v = new Video('b')  // will create new obj

hence this is obj scope

if callback in method then that will be window be the this

and in foreach method in callback we can use this as second arguament

using call method we use some other function on other object

with arrow function , this will take scope from outer function and use that