Terminology

Barrel

A barrel is a way to rollup exports from several modules into a single convenient module. The barrel itself is a module file that re-exports selected exports of other modules.

Module Resolution

Module resolution is the process the compiler uses to figure out what an import refers to. Consider an import statement like import { a } from "moduleA"; in order to check any use of a, the compiler needs to know exactly what it represents, and will need to check its definition moduleA.

At this point, the compiler will ask “what’s the shape of moduleA?” While this sounds straightforward, moduleA could be defined in one of your own .ts/.tsx files, or in a .d.ts that your code depends on.

Type Coercion

Type Coercion refers to the process of automatic or implicit conversion of values from one data type to another.

Two types of equalities in JavaScript

When discussing object comparisons in JavaScript, there are two types of equalities one must be aware of:

• Referential equality: Determines whether the two provided operands refer to the same reference/object instance.
• Deep equality: Determines whether objects are equal by comparing each property in the operands.

Referential equality can be determined with equality operators such as strict equality (===) or coercive equality (==)