reading-notes

Putting It All Together

What is the single responsibility principle and how does it apply to components?
- a component should ideally only do one thing
- If it ends up growing, it should be decomposed into smaller sub-components
What does it mean to build a ‘static’ version of your application?
- a version that takes your data model and renders the UI but has no interactivity
Once you have a static application, what do you need to add?
- Interactivity
What are the three questions you can ask to determine if something is state?
- Is it passed in from a parent via props? If so, it probably isn’t state.
- Does it remain unchanged over time? If so, it probably isn’t state.
- Can you compute it based on any other state or props in your component? If so, it isn’t state.
How can you identify where state needs to live?
- Identify every component that renders something based on that state.
- Find a common owner component (a single component above all the components that need the state in the hierarchy).
- Either the common owner or another component higher up in the hierarchy should own the state.
- If you can’t find a component where it makes sense to own the state, create a new component solely for holding the state and add it somewhere in the hierarchy above the common owner component.

What is a “higher-order function”?
- Functions that operate on other functions, either by taking them as arguments or by returning them
Explore the greaterThan function as defined in the reading. In your own words, what is line 2 of this function doing?
- an arrow function evaluating if a yet to be defined(passed?) variable is greater than n
Explain how either map or reduce operates, with regards to higher-order functions.
- map is a standard array method that takes in an array (the one you use to call it) and some operative function (the arg you pass in), and returns a new array of the items output from the operative function