In functional composition, the output of one function serves as the input for the next one. This is a key concept in functional programming, where functions are chained together to perform a series of transformations on data.

To optimize for tree shaking, individually exporting functions (export function util1() {}) allows dead code elimination, ensuring only the used functions are included in the final bundle.

Arrow functions inherit the this value from their lexical scope, which means the scope in which they were defined. This can lead to unexpected behavior when used in object methods.

Node.js uses the .mjs file extension for ES6 modules to differentiate them from CommonJS modules that typically use the .js extension. This helps Node.js to identify the module type and apply the appropriate module loading mechanism.

Yes, a static method in a parent class can be overridden in a child class. However, it's important to note that static methods are associated with the class itself rather than instances, and the child class can provide its own implementation of the static method, effectively overriding the one in the parent class.

Yes, default parameters in ES6 can be expressions or function calls. This enables dynamic default values based on the evaluation of expressions or the result of function calls. It provides flexibility and allows for more sophisticated default values in function parameters.

Composition in ES6 involves creating objects by combining multiple objects that provide functionality. This promotes a modular and reusable code structure by assembling smaller pieces to form more complex objects.

In ES6, the shorthand for method properties allows omitting the 'function' keyword when defining methods in object literals. It enhances code readability by providing a more concise syntax for method definitions within objects. This syntactic sugar simplifies the declaration of methods in objects, making the code cleaner and more modern.

The concept of referential transparency is essential in understanding how functions are combined in functional composition. Referential transparency means that a function, given the same inputs, will always return the same output, allowing for easier reasoning about the behavior of composed functions.

The spread operator can be used to clone an array without mutating the original array. It creates a shallow copy, meaning nested objects are still references, but the outer array is a new instance.