🟨JavaScript variable scope

determining the "jurisdiction" of a variable

Depending on where it gets declared, a variable "exists" (i.e. is accessible) only within its scope, which varies based on which set of brackets it "resides" in:

• global scope variable

  • a variable that we can access (use or call) from anywhere

    • usually outside of a function at the beginning of a script file

    • often declared using the keyword var before the variable name

      • a variable with letcould still have a global scope

• block scope variable

  • a variable that we can access inside the set of curly braces ("the block") we declare it in

    • declared using either constor let in ES6

  • trying to access this variable outside of the block will result in an error

• local scope variable

  • a variable that we can access inside a function and only inside that function

    • declared also using constor letin ES6