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.level !== undefined) {
  14                         rows = rows.filter(row => row[1] <= this.preset.level);
  15                 }
  16                 return rows.shuffle();
  17         }
  18
  19         load(dataurl) {
  20                 this.preset = {};
  21                 fetch(dataurl).then(res => res.json()).then(json => {
  22                         this.words = this.dataselect(json)
  23                         this.setup();
  24                 });
  25         }
  26
  27         constructor(dataurl) {
  28                 this.load(dataurl);
  29         }
  30 }