What is the meaning of sign || in javascript?

Answer 1

The sign "||" means OR.
Similiar to AND "&&".

Example:
if (a || b) {
// code
}

This code will run if a or b are true.

Answer 2

It's a sign for *OR*
It is used when you want atleast 1 condition as true to run the program

a=1
b=2
a==1||b==1
If you set this condition then your program will be executed because one of the two conditions is true