Generic types inside function body doesn't work in TS?-CodePudding

I'm trying to reuse a generic inside a function body, but I'm getting an error, why is this happening?

Example:

type OptionsArray<T> =  T[]

type Option = {
  name: string
}


// Why I get error here if OptionValueType contain name prop?
const filterName = <OptionValueType,>(options:OptionsArray<OptionValueType>) => options.map(el=>el.name)

export const filterOptions = <OptionValueType,>(options: OptionsArray<OptionValueType>, filterBy: string) : OptionsArray<OptionValueType> => {
    if (filterBy === '') {
        return [...options];
    } else {
        const filteredOptions = filterName<OptionValueType>(options);
      
        return [...filteredOptions];
    }
};

filterOptions<Option>([{name: 'Alex'}], 'name')

Is there any way to use generic types inside functions?

CodePudding user response：

You did not give your generic type a constraint:

const filterName = <OptionValueType extends Option>(options: OptionsArray<OptionValueType>) => options.map((el) => el.name);