fsrs4anki_scheduler.js

// FSRS4Anki v5.3.4 Scheduler Qt6
set_version();
// The latest version will be released on /~https://github.com/open-spaced-repetition/fsrs4anki/releases/latest

// Configuration Start

const deckParams = [
  {
    // Default parameters of FSRS4Anki for global
    "deckName": "global config for FSRS4Anki",
    "w": [0.40255, 1.18385, 3.173, 15.69105, 7.1949, 0.5345, 1.4604, 0.0046, 1.54575, 0.1192, 1.01925,
      1.9395, 0.11, 0.29605, 2.2698, 0.2315, 2.9898, 0.51655, 0.6621],
    // The above parameters can be optimized via FSRS4Anki optimizer.
    // For details about the parameters, please see: /~https://github.com/open-spaced-repetition/fsrs4anki/wiki/The-Algorithm
    // User's custom parameters for global
    "requestRetention": 0.9, // recommended setting: 0.75 ~ 0.95
    "maximumInterval": 36500,
    // FSRS only modifies the long-term scheduling. So (re)learning steps in deck options work as usual.
    // I recommend setting steps shorter than 1 day.
  },
  {
    // Example 1: User's custom parameters for this deck and its sub-decks.
    "deckName": "MainDeck1",
    "w": [0.40255, 1.18385, 3.173, 15.69105, 7.1949, 0.5345, 1.4604, 0.0046, 1.54575, 0.1192, 1.01925,
      1.9395, 0.11, 0.29605, 2.2698, 0.2315, 2.9898, 0.51655, 0.6621],
    "requestRetention": 0.9,
    "maximumInterval": 36500,
  },
  {
    // Example 2: User's custom parameters for this deck and its sub-decks.
    // Don't omit any keys.
    "deckName": "MainDeck2::SubDeck::SubSubDeck",
    "w": [0.40255, 1.18385, 3.173, 15.69105, 7.1949, 0.5345, 1.4604, 0.0046, 1.54575, 0.1192, 1.01925,
      1.9395, 0.11, 0.29605, 2.2698, 0.2315, 2.9898, 0.51655, 0.6621],
    "requestRetention": 0.9,
    "maximumInterval": 36500,
  }
];

// To turn off FSRS in specific decks, fill them into the skip_decks list below.
// Please don't remove it even if you don't need it.
const skip_decks = ["MainDeck3", "MainDeck4::SubDeck"];

// "Fuzz" is a small random delay applied to new intervals to prevent cards from
// sticking together and always coming up for review on the same day
const enable_fuzz = true;

// FSRS supports displaying memory states of cards.
// Enable it for debugging if you encounter something wrong.
const display_memory_state = false;

// Configuration End

debugger;

// display if FSRS is enabled
if (display_memory_state) {
  const prev = document.getElementById('FSRS_status')
  if (prev) { prev.remove(); }
  var fsrs_status = document.createElement('span');
  fsrs_status.innerHTML = "<br>FSRS enabled";
  fsrs_status.id = "FSRS_status";
  fsrs_status.style.cssText = "font-size:12px;opacity:0.5;font-family:monospace;text-align:left;line-height:1em;";
  document.body.appendChild(fsrs_status);
  document.getElementById("qa").style.cssText += "min-height:50vh;";
}
let params = {};
// get the name of the card's deck
if (deck_name = get_deckname()) {
  if (display_memory_state) {
    fsrs_status.innerHTML += "<br>Deck name: " + deck_name;
  }
  for (const i of skip_decks) {
    if (deck_name.startsWith(i)) {
      fsrs_status.innerHTML = fsrs_status.innerHTML.replace("FSRS enabled", "FSRS disabled");
      return;
    }
  }
  // Arrange the deckParams of sub-decks in front of their parent decks.
  deckParams.sort(function (a, b) {
    return -a.deckName.localeCompare(b.deckName);
  });
  for (let i = 0; i < deckParams.length; i++) {
    if (deck_name.startsWith(deckParams[i]["deckName"])) {
      params = deckParams[i];
      break;
    }
  }
} else {
  if (display_memory_state) {
    fsrs_status.innerHTML += "<br>Deck name not found";
  }
}
if (Object.keys(params).length === 0) {
  params = deckParams.find(deck => deck.deckName === "global config for FSRS4Anki");
}
var w = params["w"];
var requestRetention = params["requestRetention"];
var maximumInterval = params["maximumInterval"];
const DECAY = -0.5;
const FACTOR = 0.9 ** (1 / DECAY) - 1;
// global fuzz factor for all ratings.
const fuzz_factor = set_fuzz_factor();
const ratings = {
  "again": 1,
  "hard": 2,
  "good": 3,
  "easy": 4
};
// For new cards
if (is_new()) {
  init_states();
  const good_interval = next_interval(customData.good.s);
  const easy_interval = Math.max(next_interval(customData.easy.s), good_interval + 1);
  if (states.good.normal?.review) {
    states.good.normal.review.scheduledDays = good_interval;
  }
  if (states.easy.normal?.review) {
    states.easy.normal.review.scheduledDays = easy_interval;
  }
  // For learning/relearning cards
} else if (is_learning()) {
  // Init states if the card didn't contain customData
  if (is_empty()) {
    init_states();
  }
  const last_d = customData.again.d;
  const last_s = customData.again.s;
  customData.again.d = next_difficulty(last_d, "again");
  customData.again.s = next_short_term_stability(last_s, ratings["again"]);
  customData.hard.d = next_difficulty(last_d, "hard");
  customData.hard.s = next_short_term_stability(last_s, ratings["hard"]);
  customData.good.d = next_difficulty(last_d, "good");
  customData.good.s = next_short_term_stability(last_s, ratings["good"]);
  customData.easy.d = next_difficulty(last_d, "easy");
  customData.easy.s = next_short_term_stability(last_s, ratings["easy"]);
  const good_interval = next_interval(customData.good.s);
  const easy_interval = Math.max(next_interval(customData.easy.s), good_interval + 1);
  if (states.good.normal?.review) {
    states.good.normal.review.scheduledDays = good_interval;
  }
  if (states.easy.normal?.review) {
    states.easy.normal.review.scheduledDays = easy_interval;
  }
  // For review cards
} else if (is_review()) {
  // Convert the interval and factor to stability and difficulty if the card didn't contain customData
  if (is_empty()) {
    convert_states();
  }
  const interval = states.current.normal?.review.elapsedDays ? states.current.normal.review.elapsedDays : states.current.filtered.rescheduling.originalState.review.elapsedDays;
  const last_d = customData.again.d;
  const last_s = customData.again.s;
  const retrievability = forgetting_curve(interval, last_s);
  if (display_memory_state) {
    fsrs_status.innerHTML += "<br>D: " + last_d + "<br>S: " + last_s + "<br>R: " + (retrievability * 100).toFixed(2) + "%";
  }
  customData.again.d = next_difficulty(last_d, "again");
  customData.again.s = next_forget_stability(last_d, last_s, retrievability);
  customData.hard.d = next_difficulty(last_d, "hard");
  customData.hard.s = next_recall_stability(last_d, last_s, retrievability, "hard");
  customData.good.d = next_difficulty(last_d, "good");
  customData.good.s = next_recall_stability(last_d, last_s, retrievability, "good");
  customData.easy.d = next_difficulty(last_d, "easy");
  customData.easy.s = next_recall_stability(last_d, last_s, retrievability, "easy");
  let hard_interval = next_interval(customData.hard.s);
  let good_interval = next_interval(customData.good.s);
  let easy_interval = next_interval(customData.easy.s);
  hard_interval = Math.min(hard_interval, good_interval)
  good_interval = Math.max(good_interval, hard_interval + 1);
  easy_interval = Math.max(easy_interval, good_interval + 1);
  if (states.hard.normal?.review) {
    states.hard.normal.review.scheduledDays = hard_interval;
  }
  if (states.good.normal?.review) {
    states.good.normal.review.scheduledDays = good_interval;
  }
  if (states.easy.normal?.review) {
    states.easy.normal.review.scheduledDays = easy_interval;
  }
}
function constrain_difficulty(difficulty) {
  return Math.min(Math.max(+difficulty.toFixed(2), 1), 10);
}
function apply_fuzz(ivl) {
  if (!enable_fuzz || ivl < 2.5) return ivl;
  ivl = Math.round(ivl);
  let min_ivl = Math.max(2, Math.round(ivl * 0.95 - 1));
  let max_ivl = Math.round(ivl * 1.05 + 1);
  if (is_review()) {
    const scheduledDays = states.current.normal?.review.scheduledDays ? states.current.normal.review.scheduledDays : states.current.filtered.rescheduling.originalState.review.scheduledDays;
    if (ivl > scheduledDays) {
      min_ivl = Math.max(min_ivl, scheduledDays + 1);
    }
  }
  return Math.floor(fuzz_factor * (max_ivl - min_ivl + 1) + min_ivl);
}
function forgetting_curve(elpased_days, stability) {
  return Math.pow(1 + FACTOR * elpased_days / stability, DECAY);
}
function next_interval(stability) {
  const new_interval = apply_fuzz(stability / FACTOR * (Math.pow(requestRetention, 1 / DECAY) - 1));
  return Math.min(Math.max(Math.round(new_interval), 1), maximumInterval);
}
function linear_damping(delta_d, old_d) {
  return delta_d * (10 - old_d) / 9
}
function next_difficulty(d, rating) {
  let delta_d = - w[6] * (ratings[rating] - 3);
  let next_d = d + linear_damping(delta_d, d);
  return constrain_difficulty(mean_reversion(init_difficulty("easy"), next_d));
}
function mean_reversion(init, current) {
  return w[7] * init + (1 - w[7]) * current;
}
function next_recall_stability(d, s, r, rating) {
  let hardPenalty = rating === "hard" ? w[15] : 1;
  let easyBonus = rating === "easy" ? w[16] : 1;
  return +(s * (1 + Math.exp(w[8]) *
    (11 - d) *
    Math.pow(s, -w[9]) *
    (Math.exp((1 - r) * w[10]) - 1) *
    hardPenalty *
    easyBonus)).toFixed(2);
}
function next_forget_stability(d, s, r) {
  let sMin = s / Math.exp(w[17] * w[18]);
  return +Math.min(w[11] *
    Math.pow(d, -w[12]) *
    (Math.pow(s + 1, w[13]) - 1) *
    Math.exp((1 - r) * w[14]), sMin).toFixed(2);
}
function next_short_term_stability(s, rating) {
  return +(s * Math.exp(w[17] * (rating - 3 + w[18]))).toFixed(2);
}
function init_states() {
  customData.again.d = init_difficulty("again");
  customData.again.s = init_stability("again");
  customData.hard.d = init_difficulty("hard");
  customData.hard.s = init_stability("hard");
  customData.good.d = init_difficulty("good");
  customData.good.s = init_stability("good");
  customData.easy.d = init_difficulty("easy");
  customData.easy.s = init_stability("easy");
}
function init_difficulty(rating) {
  return +constrain_difficulty(w[4] - Math.exp(w[5] * (ratings[rating] - 1)) + 1).toFixed(2);
}
function init_stability(rating) {
  return +Math.max(w[ratings[rating] - 1], 0.1).toFixed(2);
}
function convert_states() {
  const scheduledDays = states.current.normal ? states.current.normal.review.scheduledDays : states.current.filtered.rescheduling.originalState.review.scheduledDays;
  const easeFactor = states.current.normal ? states.current.normal.review.easeFactor : states.current.filtered.rescheduling.originalState.review.easeFactor;
  const old_s = +Math.max(scheduledDays, 0.1).toFixed(2);
  const old_d = constrain_difficulty(11 - (easeFactor - 1) / (Math.exp(w[8]) * Math.pow(old_s, -w[9]) * (Math.exp(0.1 * w[10]) - 1)));
  customData.again.d = old_d;
  customData.again.s = old_s;
  customData.hard.d = old_d;
  customData.hard.s = old_s;
  customData.good.d = old_d;
  customData.good.s = old_s;
  customData.easy.d = old_d;
  customData.easy.s = old_s;
}
function is_new() {
  if (states.current.normal?.new !== undefined) {
    if (states.current.normal?.new !== null) {
      return true;
    }
  }
  if (states.current.filtered?.rescheduling?.originalState !== undefined) {
    if (Object.hasOwn(states.current.filtered?.rescheduling?.originalState, 'new')) {
      return true;
    }
  }
  return false;
}
function is_learning() {
  if (states.current.normal?.learning !== undefined) {
    if (states.current.normal?.learning !== null) {
      return true;
    }
  }
  if (states.current.filtered?.rescheduling?.originalState !== undefined) {
    if (Object.hasOwn(states.current.filtered?.rescheduling?.originalState, 'learning')) {
      return true;
    }
  }
  if (states.current.normal?.relearning !== undefined) {
    if (states.current.normal?.relearning !== null) {
      return true;
    }
  }
  if (states.current.filtered?.rescheduling?.originalState !== undefined) {
    if (Object.hasOwn(states.current.filtered?.rescheduling?.originalState, 'relearning')) {
      return true;
    }
  }
  return false;
}
function is_review() {
  if (states.current.normal?.review !== undefined) {
    if (states.current.normal?.review !== null) {
      return true;
    }
  }
  if (states.current.filtered?.rescheduling?.originalState !== undefined) {
    if (Object.hasOwn(states.current.filtered?.rescheduling?.originalState, 'review')) {
      return true;
    }
  }
  return false;
}
function is_empty() {
  return !customData.again.d | !customData.again.s | !customData.hard.d | !customData.hard.s | !customData.good.d | !customData.good.s | !customData.easy.d | !customData.easy.s;
}
function set_version() {
  const version = "v5.3.4";
  customData.again.v = version;
  customData.hard.v = version;
  customData.good.v = version;
  customData.easy.v = version;
}
function get_deckname() {
  if (typeof ctx !== 'undefined' && ctx.deckName) {
    return ctx.deckName;
  } else if (document.getElementById("deck") !== null && document.getElementById("deck").getAttribute("deck_name")) {
    return document.getElementById("deck").getAttribute("deck_name");
  } else {
    return null;
  }
}
function get_seed() {
  if (!customData.again.seed | !customData.hard.seed | !customData.good.seed | !customData.easy.seed) {
    if (typeof ctx !== 'undefined' && ctx.seed) {
      return ctx.seed;
    } else {
      return document.getElementById("qa").innerText;
    }
  } else {
    return customData.good.seed;
  }
}
function set_fuzz_factor() {
  // Note: Originally copied from seedrandom.js package (/~https://github.com/davidbau/seedrandom)
  !function(f,a,c){var s,l=256,p="random",d=c.pow(l,6),g=c.pow(2,52),y=2*g,h=l-1;function n(n,t,r){function e(){for(var n=u.g(6),t=d,r=0;n<g;)n=(n+r)*l,t*=l,r=u.g(1);for(;y<=n;)n/=2,t/=2,r>>>=1;return(n+r)/t}var o=[],i=j(function n(t,r){var e,o=[],i=typeof t;if(r&&"object"==i)for(e in t)try{o.push(n(t[e],r-1))}catch(n){}return o.length?o:"string"==i?t:t+"\0"}((t=1==t?{entropy:!0}:t||{}).entropy?[n,S(a)]:null==n?function(){try{var n;return s&&(n=s.randomBytes)?n=n(l):(n=new Uint8Array(l),(f.crypto||f.msCrypto).getRandomValues(n)),S(n)}catch(n){var t=f.navigator,r=t&&t.plugins;return[+new Date,f,r,f.screen,S(a)]}}():n,3),o),u=new m(o);return e.int32=function(){return 0|u.g(4)},e.quick=function(){return u.g(4)/4294967296},e.double=e,j(S(u.S),a),(t.pass||r||function(n,t,r,e){return e&&(e.S&&v(e,u),n.state=function(){return v(u,{})}),r?(c[p]=n,t):n})(e,i,"global"in t?t.global:this==c,t.state)}function m(n){var t,r=n.length,u=this,e=0,o=u.i=u.j=0,i=u.S=[];for(r||(n=[r++]);e<l;)i[e]=e++;for(e=0;e<l;e++)i[e]=i[o=h&o+n[e%r]+(t=i[e])],i[o]=t;(u.g=function(n){for(var t,r=0,e=u.i,o=u.j,i=u.S;n--;)t=i[e=h&e+1],r=r*l+i[h&(i[e]=i[o=h&o+t])+(i[o]=t)];return u.i=e,u.j=o,r})(l)}function v(n,t){return t.i=n.i,t.j=n.j,t.S=n.S.slice(),t}function j(n,t){for(var r,e=n+"",o=0;o<e.length;)t[h&o]=h&(r^=19*t[h&o])+e.charCodeAt(o++);return S(t)}function S(n){return String.fromCharCode.apply(0,n)}if(j(c.random(),a),"object"==typeof module&&module.exports){module.exports=n;try{s=require("crypto")}catch(n){}}else"function"==typeof define&&define.amd?define(function(){return n}):c["seed"+p]=n}("undefined"!=typeof self?self:this,[],Math);
  // MIT License
  // Copyright 2019 David Bau.
  // Permission is hereby granted, free of charge, to any person obtaining a copy
  // of this software and associated documentation files (the "Software"), to deal
  // in the Software without restriction, including without limitation the rights
  // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  // copies of the Software, and to permit persons to whom the Software is
  // furnished to do so, subject to the following conditions:
  // The above copyright notice and this permission notice shall be included in all
  // copies or substantial portions of the Software.
  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  // SOFTWARE.
  let seed = get_seed();
  const generator = new Math.seedrandom(seed);
  const fuzz_factor = generator();
  seed = Math.round(fuzz_factor * 10000);
  customData.again.seed = (seed + 1) % 10000;
  customData.hard.seed = (seed + 2) % 10000;
  customData.good.seed = (seed + 3) % 10000;
  customData.easy.seed = (seed + 4) % 10000;
  return fuzz_factor;
}