My 2 Cents What Are Undeclared And Undefined Variables In Javascript?

steve taylor

White Belt
Undeclared variables are variable that do not exist in a program and are not declared. If the program read the value of an undeclared variable, then error occurred during run time.

Undefined variables are variable that are declared in the program but not have been given any value. If the program read the value of an undefined variable, then undefined value is returned to output.

Swati Mishra

Content Writer
Undeclared variable can be declared anytime when a programmer find it to be done and the undefined can be given value at anytime an activity need to be take place. It is a good practice to save the memory allocation in some way.