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typescript

TS2344: Type 'X' does not satisfy the constraint 'Y'

You're passing a type argument to a generic function or class that doesn't meet the constraints defined by the generic's extends clause. The constraint specifies the minimum shape a type must have to be used with that generic.

Common causes

Passing a primitive type (string, number) where the generic requires an object shape
The type is missing properties required by the constraint interface
Using a union type as a type argument when the constraint requires a single compatible type
A generic constraint changed in a library update and your type argument no longer satisfies it

How to fix it

Make your type satisfy the constraint by adding the required properties
Extend the required interface: interface MyType extends RequiredConstraint { ... }
Check what the constraint requires: hover over the generic parameter in your editor
Reconsider whether you're using the right type argument — you may need a different type

Example

function getProperty<T extends object, K extends keyof T>(obj: T, key: K) { return obj[key]; }
getProperty('not an object', 'length');
// error TS2344: Type 'string' does not satisfy the constraint 'object'.

Passing a string where T extends object — strings don't satisfy the object constraint

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