a small Persistant storage i wrote for minecrafts gametest 1.18.2 (free for anyone to use with credit)

GametestDB.ts

import * as MC from "mojang-minecraft";
interface IStringSaver {
  save(value: string): void;
  load(): string;
  hasData(): boolean;
}
class MemorySaver implements IStringSaver {
  private _data: string;
  constructor() {
    this._data = "";
  }
  public save(value: string): void {
    this._data = value;
  }
  public load(): string {
    return this._data;
  }
  public hasData(): boolean {
    return this._data !== "";
  }
}
class EntityNameSaver implements IStringSaver {
  private _entities: MC.Entity[] = [];
  constructor(private position: MC.BlockLocation, private prefix: string = "") {
    if (this.prefix.includes("|")) {
      throw new Error("Prefix cannot contain |");
    }
    this.syncEntities();
  }
  private syncEntities() {
    this._entities = MC.World.getDimension("overworld")
      .getEntitiesAtBlockLocation(this.position)
      .filter((entity) => entity.nameTag.startsWith("DB" + this.prefix));
  }
  public save(value: string): void {
    this.syncEntities();
    let chunkSize = 32767 - 8 - this.prefix.length;
    let chunkCount = Math.ceil(value.length / chunkSize);
    if (this._entities.length < chunkCount) {
      for (let i = this._entities.length; i < chunkCount; i++) {
        let e = MC.World.getDimension("overworld").spawnEntity(
          "minecraft:armor_stand",
          this.position
        );
        // this is an empty payload, if for some reason one or more of these are not assigned data they will not effect the output
        e.nameTag = "DB" + this.prefix + "|99999";
        this._entities.push(e);
      }
    } else if (this._entities.length > chunkCount) {
      for (let i = this._entities.length - 1; i > chunkCount; i--) {
        this._entities[i].kill();
      }
      this._entities.splice(chunkCount);
    }
    for (let i = 0; i < chunkCount; i++) {
      let chunk = value.substr(i * chunkSize, chunkSize);
      this._entities[i].nameTag =
        "DB" + this.prefix + "|" + i.toString().padStart(5, "0") + chunk;
    }
  }
  public load(): string {
    this.syncEntities();
    let sortedEntities = this._entities.sort(
      (a, b) =>
        parseInt(
          a.nameTag.substring(3 + this.prefix.length, 8 + this.prefix.length)
        ) -
        parseInt(
          b.nameTag.substring(3 + this.prefix.length, 8 + this.prefix.length)
        )
    );
    let content = sortedEntities
      .map((ent) => ent.nameTag.substring(8 + this.prefix.length))
      .join("");
    return content;
  }
  public hasData(): boolean {
    this.syncEntities();
    return this._entities.length > 0;
  }
}
class DB<T extends IStringSaver> {
  public static tickQueue: Function[] = [];
  private value: Record<string, any> | null = null;
  private lastSaveTime = 0;
  private hasSaveQueued: boolean;
  constructor(private saveHandler: T) {
    this.value = null;
    this.lastSaveTime = Date.now();
    this.hasSaveQueued = false;
  }
  public queueSave(): void {
    if (!this.hasSaveQueued) {
      const handler = (e) => {
        // if (this.lastSaveTime < Date.now() - 1000) {
        this.saveData();
        this.lastSaveTime = Date.now();
        this.hasSaveQueued = false;
        DB.tickQueue.splice(DB.tickQueue.indexOf(handler), 1);
        // }
        // MC.Commands.run(`say hi`, MC.World.getDimension("overworld"));
      };
      DB.tickQueue.push(handler);
      this.hasSaveQueued = true;
    }
  }
  private maybeLoadData() {
    if (this.value !== null) {
      return;
    }
    let data = this.saveHandler.hasData() ? this.saveHandler.load() : "{}";
    this.value = JSON.parse(data);
  }
  public saveData(): void {
    this.saveHandler.save(JSON.stringify(this.value));
  }
  public get(key: string): any {
    this.maybeLoadData();
    return this.value[key];
  }
  public set(key: string, value: any): void {
    this.maybeLoadData();
    this.value[key] = value;
    this.queueSave();
  }
  public has(key: string): boolean {
    this.maybeLoadData();
    return this.value.hasOwnProperty(key);
  }
  public delete(key: string): void {
    this.maybeLoadData();
    delete this.value[key];
    this.queueSave();
  }
  public clear(): void {
    this.maybeLoadData();
    this.value = {};
    this.queueSave();
  }
  public keys(): string[] {
    this.maybeLoadData();
    return Object.keys(this.value);
  }
  public size(): number {
    return this.keys().length;
  }
  public values(): any[] {
    this.maybeLoadData();
    return Object.values(this.value);
  }
  public entries(): [string, any][] {
    this.maybeLoadData();
    return Object.entries(this.value);
  }
  public forEach(
    callback: (value: any, key: string, map: DB<T>) => void,
    thisArg?: any
  ): void {
    this.maybeLoadData();
    Object.keys(this.value).forEach((key) => {
      callback(this.value[key], key, this);
    });
  }
  debug() {
    return this.saveHandler.load().length;
  }
}
MC.World.events.tick.subscribe(() => {
  for (const handler of DB.tickQueue) {
    try {
      handler();
    } catch (e) {
      console.warn(e.message, e.stack);
    }
  }
});

Store.js

// same as above but not minified
import * as MC from "mojang-minecraft";
class MemorySaver {
    constructor() {
        this._data = "";
    }
    save(value) {
        this._data = value;
    }
    load() {
        return this._data;
    }
    hasData() {
        return this._data !== "";
    }
}
class EntityNameSaver {
    constructor(position, prefix = "") {
        this.position = position;
        this.prefix = prefix;
        this._entities = [];
        if (this.prefix.includes("|")) {
            throw new Error("Prefix cannot contain |");
        }
        this.syncEntities();
    }
    syncEntities() {
        this._entities = MC.World.getDimension("overworld")
            .getEntitiesAtBlockLocation(this.position)
            .filter((entity) => entity.nameTag.startsWith("DB" + this.prefix));
    }
    save(value) {
        this.syncEntities();
        let chunkSize = 32767 - 8 - this.prefix.length;
        let chunkCount = Math.ceil(value.length / chunkSize);
        if (this._entities.length < chunkCount) {
            for (let i = this._entities.length; i < chunkCount; i++) {
                let e = MC.World.getDimension("overworld").spawnEntity("minecraft:armor_stand", this.position);
                // this is an empty payload, if for some reason one or more of these are not assigned data they will not effect the output
                e.nameTag = "DB" + this.prefix + "|99999";
                this._entities.push(e);
            }
        }
        else if (this._entities.length > chunkCount) {
            for (let i = this._entities.length - 1; i > chunkCount; i--) {
                this._entities[i].kill();
            }
            this._entities.splice(chunkCount);
        }
        for (let i = 0; i < chunkCount; i++) {
            let chunk = value.substr(i * chunkSize, chunkSize);
            this._entities[i].nameTag =
                "DB" + this.prefix + "|" + i.toString().padStart(5, "0") + chunk;
        }
    }
    load() {
        this.syncEntities();
        let sortedEntities = this._entities.sort((a, b) => parseInt(a.nameTag.substring(3 + this.prefix.length, 8 + this.prefix.length)) -
            parseInt(b.nameTag.substring(3 + this.prefix.length, 8 + this.prefix.length)));
        let content = sortedEntities
            .map((ent) => ent.nameTag.substring(8 + this.prefix.length))
            .join("");
        return content;
    }
    hasData() {
        this.syncEntities();
        return this._entities.length > 0;
    }
}
class DB {
    constructor(saveHandler) {
        this.saveHandler = saveHandler;
        this.value = null;
        this.lastSaveTime = 0;
        this.value = null;
        this.lastSaveTime = Date.now();
        this.hasSaveQueued = false;
    }
    queueSave() {
        if (!this.hasSaveQueued) {
            const handler = (e) => {
                if (this.lastSaveTime < Date.now() - 1000) {
                this.saveData();
                this.lastSaveTime = Date.now();
                this.hasSaveQueued = false;
                DB.tickQueue.splice(DB.tickQueue.indexOf(handler), 1);
                }
            };
            DB.tickQueue.push(handler);
            this.hasSaveQueued = true;
        }
    }
    maybeLoadData() {
        if (this.value !== null) {
            return;
        }
        let data = this.saveHandler.hasData() ? this.saveHandler.load() : "{}";
        this.value = JSON.parse(data);
    }
    saveData() {
        this.saveHandler.save(JSON.stringify(this.value));
    }
    get(key) {
        this.maybeLoadData();
        return this.value[key];
    }
    set(key, value) {
        this.maybeLoadData();
        this.value[key] = value;
        this.queueSave();
    }
    has(key) {
        this.maybeLoadData();
        return this.value.hasOwnProperty(key);
    }
    delete(key) {
        this.maybeLoadData();
        delete this.value[key];
        this.queueSave();
    }
    clear() {
        this.maybeLoadData();
        this.value = {};
        this.queueSave();
    }
    keys() {
        this.maybeLoadData();
        return Object.keys(this.value);
    }
    size() {
        return this.keys().length;
    }
    values() {
        this.maybeLoadData();
        return Object.values(this.value);
    }
    entries() {
        this.maybeLoadData();
        return Object.entries(this.value);
    }
    forEach(callback, thisArg) {
        this.maybeLoadData();
        Object.keys(this.value).forEach((key) => {
            callback(this.value[key], key, this);
        });
    }
    debug() {
        return this.saveHandler.load().length;
    }
}
DB.tickQueue = [];
MC.World.events.tick.subscribe(() => {
    for (const handler of DB.tickQueue) {
        try {
            handler();
        }
        catch (e) {
            console.warn(e.message, e.stack);
        }
    }
});
export { DB as DataStore, MemorySaver, EntityNameSaver };

Store.min.js

// this is a module you can add to your gametest library that adds the PersistantStorage as DataStore
import*as t from"mojang-minecraft";class e{constructor(){this._data=""}save(t){this._data=t}load(){return this._data}hasData(){return""!==this._data}}class s{constructor(t,e=""){if(this.position=t,this.prefix=e,this._entities=[],this.prefix.includes("|"))throw new Error("Prefix cannot contain |");this.syncEntities()}syncEntities(){this._entities=t.World.getDimension("overworld").getEntitiesAtBlockLocation(this.position).filter((t=>t.nameTag.startsWith("DB"+this.prefix)))}save(e){this.syncEntities();let s=32759-this.prefix.length,i=Math.ceil(e.length/s);if(this._entities.length<i)for(let e=this._entities.length;e<i;e++){let e=t.World.getDimension("overworld").spawnEntity("minecraft:armor_stand",this.position);e.nameTag="DB"+this.prefix+"|99999",this._entities.push(e)}else if(this._entities.length>i){for(let t=this._entities.length-1;t>i;t--)this._entities[t].kill();this._entities.splice(i)}for(let t=0;t<i;t++){let i=e.substr(t*s,s);this._entities[t].nameTag="DB"+this.prefix+"|"+t.toString().padStart(5,"0")+i}}load(){return this.syncEntities(),this._entities.sort(((t,e)=>parseInt(t.nameTag.substring(3+this.prefix.length,8+this.prefix.length))-parseInt(e.nameTag.substring(3+this.prefix.length,8+this.prefix.length)))).map((t=>t.nameTag.substring(8+this.prefix.length))).join("")}hasData(){return this.syncEntities(),this._entities.length>0}}class i{constructor(t){this.saveHandler=t,this.value=null,this.lastSaveTime=0,this.value=null,this.lastSaveTime=Date.now(),this.hasSaveQueued=!1}queueSave(){if(!this.hasSaveQueued){const t=e=>{this.lastSaveTime<Date.now()-1e3&&(this.saveData(),this.lastSaveTime=Date.now(),this.hasSaveQueued=!1,i.tickQueue.splice(i.tickQueue.indexOf(t),1))};i.tickQueue.push(t),this.hasSaveQueued=!0}}maybeLoadData(){if(null!==this.value)return;let t=this.saveHandler.hasData()?this.saveHandler.load():"{}";this.value=JSON.parse(t)}saveData(){this.saveHandler.save(JSON.stringify(this.value))}get(t){return this.maybeLoadData(),this.value[t]}set(t,e){this.maybeLoadData(),this.value[t]=e,this.queueSave()}has(t){return this.maybeLoadData(),this.value.hasOwnProperty(t)}delete(t){this.maybeLoadData(),delete this.value[t],this.queueSave()}clear(){this.maybeLoadData(),this.value={},this.queueSave()}keys(){return this.maybeLoadData(),Object.keys(this.value)}size(){return this.keys().length}values(){return this.maybeLoadData(),Object.values(this.value)}entries(){return this.maybeLoadData(),Object.entries(this.value)}forEach(t,e){this.maybeLoadData(),Object.keys(this.value).forEach((e=>{t(this.value[e],e,this)}))}debug(){return this.saveHandler.load().length}}i.tickQueue=[],t.World.events.tick.subscribe((()=>{for(const t of i.tickQueue)try{t()}catch(t){console.warn(t.message,t.stack)}}));export{i as DataStore,e as MemorySaver,s as EntityNameSaver};

test.ts

const testSaver = new EntityNameSaver(
  new MC.BlockLocation(0, 200, 0),
  "TestDB"
);
const testDB = new DB(testSaver);
let deltaTimeArray = [];
//tickevent
//@ts-ignore
MC.World.events.tick.subscribe(({ currentTick, deltaTime }) => {
  for (let i = 0; i < 10000; i++) {
    testDB.set("tick" + i, Date.now());
  }
  // @ts-ignore

  deltaTimeArray.unshift(deltaTime);
  if (deltaTimeArray.length > 250) {
    deltaTimeArray.pop();
  }
  console.warn(
    "TPS" +
      (1 /
        (deltaTimeArray.reduce(
          (previousValue, currentValue) => previousValue + currentValue
        ) /
          deltaTimeArray.length) +
        "," +
        deltaTimeArray.length)
  );
});
MC.World.events.beforeChat.subscribe(({ message }) => {
  try {
    const [cmd, target, ...payloadarr] = message.split(" ");
    const payload = payloadarr.join(" ");
    if (Reflect.has(testDB, cmd)) {
      let res = testDB[cmd](target, payload);
      MC.Commands.run(
        `say testDB.${cmd}("${target}"): ${res}`,
        MC.World.getDimension("overworld")
      );
    }
  } catch (e) {
    MC.Commands.run(`say ${e.message}`, MC.World.getDimension("overworld"));
    e.stack.split("\n").forEach((element) => {
      MC.Commands.run(`say ${element}`, MC.World.getDimension("overworld"));
    });
  }
});