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This is a situation I have ran into a couple of times, it seems like it should be fairly straightforward, but I can't find a solution that doesn't set the type to any
A function takes one of two different objects as the argument, checks which object has been received, and returns the corresponding field.
This is a simplified version of the problem, but the issue is that the two objects are only distinguishable by their properties(which have no overlap), and I can't access any of the properties, because they're not present on the other type.
type Obj1 = { message: string } type Obj2 = { text: string } const getText = (obj: Obj1 |obj2): string => { if (obj.message) { return obj.message } return obj.text } 
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The "property does not exist on type union" error occurs when we try to access a property that is not present on every object in the union type. To solve the error, use a type guard to ensure the property exists on the object before accessing it.
TypeScript Union Type Narrowing To narrow a variable to a specific type, implement a type guard. Use the typeof operator with the variable name and compare it with the type you expect for the variable.
The "Property does not exist on type '{}'" error occurs when we try to access or set a property that is not contained in the object's type. To solve the error, type the object properties explicitly or use a type with variable key names.
TypeScript 1.4 gives programs the ability to combine one or two types. Union types are a powerful way to express a value that can be one of the several types. Two or more data types are combined using the pipe symbol (|) to denote a Union Type.
You have to narrow down the type. You can do so by using the in operator.
const getText = (obj: Obj1 | Obj2): string => { if ("message" in obj) { return obj.message } return obj.text } If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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