Is there a way to enforce a specific type of function with default values for some functions?
I experimented with a simple code snippet like the one below:
type MyFunc = (str: string) => number;
const myAFunc: MyFunc = (str) => Number(str);
const myBFunc: MyFunc = (str = '9999') => Number(str);
myAFunc('a');
myAFunc(); // should result in an error
myBFunc('b');
myBFunc(); // should not result in an error
However, it doesn't seem to be working. Are there any solutions available?
When working with functions A and B, it's important to consider their individual types rather than trying to fit them into the same type:
type FunctionA = (input: string) => number;
type FunctionB = (input?: string) => number;
const funcA: FunctionA = (input) => Number(input);
const funcB: FunctionB = (input = '9999') => Number(input);
funcA('example');
funcA(); // should result in an error
funcB('test');
funcB(); // should not cause an error
To allow for passing optional parameters to the function, use a "?" before the parameter type in the function signature.
type CustomFunction = (name?: string) => number;
const funcA: CustomFunction = (name) => Number(name);
const funcB: CustomFunction = (name = '9999') => Number(name);
funcA(); // NaN
funcB(); // 9999
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