u2x ·

A suite of utilities for converting unknown data to desired type.

Install

yarn add u2x

or

npm install u2x --save

Background

A design principle for reliability of system is to NEVER TRUST EXTERNAL DATA, any data obtained from external sources are untrusted.

For the frontend, external data is most likely to come from the backend.

For example,

const result = await request('...');

When you receive data from remote, you cannot trust that type of data.

If you access its property directly, like this:

console.log(result.aaa);

an exception will be thrown if the result is null or undefined.

Therefore, you can wrap u2o with this result, such as

const safeResult = u2o(result);

console.log(safeResult.aaa);

The u2o function convert any value to an object.

Wait! Is not that too simple? So why do not I wrap it with Object?

const safeResult = Object(result);

console.log(safeResult.aaa);

This code works just as well.

Yes, you are right. The u2o function is also implemented using Object, you can see the code src/u2o.ts here.

But, in TypeScript, Object always returns an any, it is a bad practis.

For example:

const safeResult = Object(result);

console.log(safeResult.aaa.bbb); // An exception will be thrown if `aaa` is `null` or `undefined`.

On an any, all properties are any (The contagiousness of any), you can not guarantee that every property is an object.

In fact, if Object(...) returns Record<PropertyKey, unknown>, that is a better definition. When you attempt to access a property from an unknown, TypeScript compiler warns you that this is an error.