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JavaScript Introduction to Programming Basics Variables

Thanapat Sorralump
Thanapat Sorralump
6,325 Points
Posted by Thanapat Sorralump
Thanapat Sorralump
6,325 Points

"Var name =..." VS "name = ..."

What is the difference of "Var name = ..." and "name = ..." ?

1 Answer

William Li
PLUS
William Li
Courses Plus Student 26,868 Points
William Li
William Li
Courses Plus Student 26,868 Points

This has to do with scope.

  • with var, you're defining the variable in current scope.
  • without var, program will think this is probably an re-assignment, it will first look within current scope for the variable carrying the same name; if failed, then it will continue the lookup in outer scope, until all the way to Global scope. If it still can't find it in Global, it will declare your variable in global scope. And it's very bad.

Always use var when declaring variable.