Glossary term
What is loosely typed (Loosely (dynamically) typed)?
loosely typed stands for Loosely (dynamically) typed.
A variable has no fixed type: the same slot can hold a number, then a string, then a function. The type belongs to the value, not the variable.
Learn it properly · JavaScript CoreLesson 6: Undefined vs Not DefinedThese sound like the same complaint — "there's nothing there" — but JavaScript treats them as two completely different situations, one safe and expected, the other a genuine error. Mixing them up is one of the most common small misunderstandings in the language.