reading-notes

Read Class 05

Reading

React Docs - Thinking in React

1. What is the single responsibility principle and how does it apply to components?
   • a component should ideally only do one thing
2. What does it mean to build a ‘static’ version of your application?
   • a build version of the UT for m the data model without adding any interactivity
3. Once you have a static application, what do you need to add?
   • state
4. What are the three questions you can ask to determine if something is state?
   • Does it remain unchanged over time?
   • Is it passed in from a parent via props?
   • Can you compute it based on existing state or props in your component?
5. How can you identify where state needs to live?
   • identify components that render something based on that state
   • find their closest common parent component
     • this would be the component above them all in the hierarchy
   • can’t seem to find the component that makes sense to hold the state?
     • make a new component strictly for that state above the common parent component!

Higher-Order Functions

1. What is a “higher-order function”?
   • functinos that operate on other functions, either by taking them as arguments or by returning them
2. Explore the greatThan function as defined in the reading. In your own words, what is line 2 of this function doing?
   • line 2 is returning the outcome of m > n comparison
3. Explain how either map or reduce operates, with regards to higher-order functions.
   • map transforms an array by applying a function to all of its elements and building a new array from the returned values. The new array will have the same length as the input array while the new content has been “mapped” to a new form by the function
   • reduce builds a value by repeatedly taking a single element from the array and combining it with the current value