Data Structures

• Chapter 4 of the book, you should give it a read.
• Arrays
  • reference
  • Dynamic.
  • integer indexed.
  • can be sparse.
  • Copy is shallow.
  • array.length is the length of the array
  • There are many methods,
    • push - adds elements to the end of the array
    • pop - removes and returns the last element.
    • findIndex(item)

  • let points=[];
    let sides = 3;
    let r = 10;
    while (sides < 20) {
         MakePoints(sides,r, points);
         DisplayPoints("polygons", points);
         sides++;
         r += 10;
    } 

  • Look at seven.js
    • Note passing points.
    • I orignally cleared points in MakePoints
      • points=[]
      • But this is allocating a new array.
      • So the pass by reference was not effective.
      • array.splice is a method that will replace elements of an array.
    • Note I am using polar coordinates to generate the points.
  • Whe looking at array methods, make sure you pay attention to the documentation
  • Many many say that they return a shallow copy.
    • This is probably what you want most of the time, but ...