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What does "extend" mean in programming?
extend is one of the most common terms in software development. This guide explains what it means, how it is used in practice, and why it matters, with real examples from the developer world.
Definition
To create a new class or interface that inherits from an existing one, gaining all its members and adding new ones. In TypeScript both classes and interfaces can be extended.
Example
"class AdminUser extends User { isAdmin = true; }"
Word forms
| Form | Type | Meaning | Example |
|---|---|---|---|
| extend | verb (infinitive) | To add functionality to an existing class or interface | "Extend the base class to add new behavior." |
| extended | past tense | Added functionality to an existing class or interface | "The Admin class extended User to inherit all base functionality." |
| extending | gerund | Adding functionality to an existing class or interface | "Extending an interface is a common way to add fields in TypeScript." |
Related terms
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