We have an array of functions that validate data.
We've defined an function type signature for the validators that looks like this:
export type ValidationFunctionSignature = ( dataMap: Map<number, CsvSelectionData> ) => IndexedMetaError | null
All the functions must be designed according to this signature.
We can then create an array of the functions:
/**
* Sequenced array of validators
*/
validators: ValidationFunctionSignature[] = [validateKeyValues,validateUniqueKeys]
Now suppose we change the return type of validateKeyValues to boolean. So it's defined like this:
function validateKeyValues(...):boolean
VSCode will now immediately notice that validateKeyValues no longer conforms to the ValidationFunctionSignature and flag it as an error.