word/quiz.js

   1 Array.prototype.shuffle = function () {
   2         for (let i = this.length - 1; i > 0; i--) {
   3                 const j = Math.floor(Math.random() * (i + 1)); // random index 0..i
   4                 [this[i], this[j]] = [this[j], this[i]]; // swap elements
   5         }
   6         return this;
   7 };
   8
   9 class WordQuiz {
  10         dataselect(json) {
  11                 // find viable rows from json data
  12                 let rows = Object.values(json);
  13                 if (this.preset.cat !== undefined) {
  14                         let cats = {}; // category lookup
  15                         for (let i in json) {
  16                                 let cat = json[i][3];
  17                                 if (!cats[cat]) cats[cat] = [];
  18                                 cats[cat].push(i)
  19                         }
  20
  21                         rows = [];
  22                         let children = cats[this.preset.cat];
  23                         for (let loop = 0; children.length && loop < 20; loop++) {
  24                                 rows.push(...children);
  25                                 children = children.map(cat => cats[cat]).filter(is => is).flat();
  26                         }
  27                         rows = rows.map(row => json[row]).filter(row => row[2]);
  28                 }
  29                 if (this.preset.level !== undefined) {
  30                         rows = rows.filter(row => row[1] <= this.preset.level);
  31                 }
  32
  33                 {
  34                         let cats = new Set();
  35                         let subcats = rows.map(row => row[3]); // direct parents
  36                         for (let loop = 0; subcats.length && loop < 20; loop++) {
  37                                 subcats.forEach(cat => cats.add(cat));
  38                                 subcats = subcats.map(row => json[row] && json[row][3]).filter(val => val); // recurse grandparents
  39                         }
  40                         rows = rows.filter(row => !cats.has(row[2])); // remove referenced categories
  41                 }
  42                 return rows.shuffle();
  43         }
  44
  45         load(dataurl) {
  46                 this.preset = {};
  47                 fetch(dataurl).then(res => res.json()).then(json => {
  48                         this.words = this.dataselect(json)
  49                         this.setup();
  50                 });
  51         }
  52
  53         constructor(dataurl) {
  54                 this.load(dataurl);
  55         }
  56 }