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JavaScript JavaScript Loops, Arrays and Objects Tracking Data Using Objects Using `for in` to Loop Through an Object's Properties

Why was Dave successful in not using "var" in his for in loop? (JS Loops, Array, Objects), 'for in' loop video

Why was Dave successful in not using "var" in his for in loop? (JS Loops, Array, Objects), 'for in' loop video

1 Answer

Steven Parker
Steven Parker
229,645 Points

The "var" wasn't necessary because JavaScript treats the assignment of an undeclared variable as an implicit global declaration. It would, however, be a "best practice" to always declare the variable explicitly. Also, if the engine were operating in "strict mode", implicit declarations are not allowed and would cause an error.