safeget-fn-parser v0.3.0

safeget-fn-parser

Access long property chains like (x) => x.a.b.c.d; safely with null/undefined coalescing. Works by parsing function text, can handle both classical JS functions and fat-arrow functions.

Available via NPM:

npm install safeget-fn-parser

    const val = safeGet(test, (x) => x.a.b.c.d.e);

Will go through the chain while it can, will return undefined if property access on a null or undefined is attempted.

This only makes sense for simple cases with . access, so no [] access is allowed.

What is the point?

Why not just wrap function invocation into try...catch? Exceptions are at-least 2 orders of magnitude slower than normal loop access (when they do throw).

Why not use generics and keyof like here? https://stackoverflow.com/a/47223501/882936

export function nullSafe<T, 
    K0 extends keyof T, 
    K1 extends keyof T[K0],
    K2 extends keyof T[K0][K1],
    ...>
    (obj: T, k0: K0, k1?: K1, k2?: K2, ...) {
        ...
    });

That approach works fine, but has flaw - VSCode won't show you such access via 'Find all references' and similar commands. For enterprise applications laden with business logic, this is bad.