Global variables: variables that can be used anywhere in the Web page (inside the function and outside the Function) are "global variables."
Variables that are defined outside the function are "global variables."
Global variables can be used outside of a function or inside a Function.
global variables automatically disappears (frees space) when the page is Closed.
Local Variable: A variable that can only be used inside a function, called a "local variable."
A "local variable" is defined inside a function and used inside a Function.
"local variables" cannot be accessed outside the Function.
the "local variable" disappears after the function is finished .
inside the function, omit the keyword var the variable defined is a "global variable".
Note: the var keyword should not be omitted, the "global variables" and "local variables" will not be clear after omitting.
JS global variables and local variables