window.variableName

Question

I am going through some code and at the beginning of the script we have var emailID = email. Later on, the code refers to emailID by going window.emailID<

Answer 1

window.variableName means that the variable is being declared at the global scope. This means any JS code will have access to this variable. Using window. is not necessary but is frequently used as a convention to denote that a variable is global.

Globals are generally to be avoided. You should define variables within the scope of functions.