Mutable

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A mutable value is one that can be changed without creating an entirely new value, in comparison with {{Glossary("immutable", "immutable values")}} .

In {{glossary("JavaScript")}} , {{Glossary("Object","objects")}}  and {{Glossary("Array","arrays")}}  are mutable by default — their properties and elements can be changed without creating a new object or array. By contrast, {{Glossary("primitive", "primitive values")}}  are immutable — once a primitive value is created, it cannot be changed, although the variable that holds it may be reassigned another value.

See also

• Immutable object on Wikipedia
• Related glossary terms:
  • {{glossary("Immutable")}}