Improve the hasProperty function
#79
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Gudahtt
commented
Feb 10, 2023
| @@ -36,6 +36,20 @@ if (isObject(unknownObject)) { | |||
| expectNotAssignable<Record<'foo', unknown>>(unknownObject); | |||
| } | |||
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| // An object is accepted after `hasProperty` is used to prove that it has the required property. | |||
| if (isObject(unknownObject) && hasProperty(unknownObject, 'foo')) { | |||
| expectAssignable<Record<'foo', unknown>>(unknownObject); | |||
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These two tests were failing before these changes
Gudahtt
commented
Feb 10, 2023
| >( | ||
| objectToCheck: ObjectToCheck, | ||
| name: Property, | ||
| ): objectToCheck is ObjectToCheck & Record<Property, unknown> => |
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Gudahtt
commented
Feb 10, 2023
| // [['foo'], 0], | ||
| // [['foo'], '0'], | ||
| ] as any[] | ||
| ] as const |
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These array test cases didn't seem relevant because they contradicted the input type.
The `hasProperty` function now tells TypeScript that the property exists, making it more effective as a type guard. A `ValidPropertyTypes` type has been added as well, for convenience.
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Gudahtt
commented
Feb 10, 2023
| @@ -32,10 +32,14 @@ export type PartialOrAbsent<Value> = Partial<Value> | null | undefined; | |||
| export type NonEmptyArray<Element> = [Element, ...Element[]]; | |||
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| /** | |||
| * A JavaScript object that is not `null`, a function, or an array. The object | |||
| * can still be an instance of a class. | |||
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Oops, this deletion was intended to be in #78. The tests added there show that instances of a class were not compatible with the RuntimeObject type.
Mrtenz
reviewed
Feb 12, 2023
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The
hasPropertyfunction now tells TypeScript that the property exists, making it more effective as a type guard.A
ValidPropertyTypestype has been added as well, for convenience.