How to Fix TypeScript Generic Error in AI-Built Apps

Generic type parameters cause confusing compilation errors. AI-generated generic code often has incorrect constraints, missing type parameters, or overly complex type hierarchies.

Error messages you might see

Type 'T' does not satisfy the constraint 'Record<string, unknown>'
Type 'string' is not assignable to type 'T'. 'T' could be instantiated with a different subtype of constraint 'string'.

Why this happens in AI-generated code

1

Missing generic constraints

AI creates generic functions without `extends` clauses, causing TypeScript to infer `unknown` for type parameters.

2

Incorrect return type narrowing

Generic functions return a broader type than the specific generic parameter, breaking type inference.

3

Over-abstracted generics

AI creates deeply nested generic types that are impossible to understand or extend correctly.

How to fix it

1

Add proper type constraints

Use `extends` to constrain generics: `function getProperty<T extends object, K extends keyof T>(obj: T, key: K): T[K]`.

2

Simplify generic hierarchies

Flatten deeply nested generics. If a type takes more than 3 generic parameters, it should probably be split up.

3

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Frequently asked questions

When should I use generics?

Use generics when a function or class needs to work with multiple types while preserving type relationships in inputs and outputs.

Why does TypeScript say my type could be instantiated differently?

You're assigning a concrete type to a generic parameter. The generic could be a more specific subtype, so TypeScript prevents the assignment.

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