ArcGIS JS customizes the accessor and uses the watchutils related method to view the attribute

Technical requirements ： Use watchUtils class ,whenTrue Related methods , Monitoring properties .

Business needs ： Map class library , You need to read an interface of the intranet , Judge whether the network is an intranet , In order to access more map resources in the intranet server in the Intranet environment . Plan to pass a logo , adopt xhr Set the ID after requesting the interface . after , Map related functions , Judge the variable before execution , Is it true, Prevent some variables from failing to complete initialization due to asynchrony .

Customize Accessor class

/**
 * 20220727
 *  Map initialization object monitoring   It is mainly used to record whether the map initialization work is completed 
 */

import Accessor from "esri/core/Accessor";
import { property, subclass } from "esri/core/accessorSupport/decorators";

@subclass("custom.MO")
class MO extends Accessor {
  private isOK: boolean = false;

  constructor() {
    super();
    this.isOK = false;
  }

  @property()
  get isIni(): boolean {
    return this.isOK;
  }

  set isIni(val: boolean) {
    const oldValue = this.get<boolean>("isIni");
    if (oldValue !== val) {
      // a setter has to update the value from the cache
    //   this.set("isIni", val);
      this.isOK = val;
      this.notifyChange("isIni");
    }
  }
}

export = MO;

Examples used in the main function

import watchUtils = require("esri/core/watchUtils");


watchUtils.whenTrue(this.mo, "isIni", () => {
      if (tp == "layerlist") {
          if (collapsed) t.expandLayerList.collapse();
          else t.expandLayerList.expand();
        }
        if (tp == "legend") {
          if (collapsed) {
            t.expandLegend.collapse();
          } else {
            t.expandLegend.expand();
          }
        }
    });

It is important to avoid the pit , An exception occurred during the test ：

It has been suspected that there is a problem with the custom class , As a result, the attribute is not obtained , A lot of information , There are many different ways of writing .  Finally, I suddenly remembered my previous post ,

ArcGIS JS TypeScript urlUtils Use of _ No overrun blog -CSDN Blog

take import watchUtils from "" Writing , Change to

import watchUtils = require("")

After testing , It can be realized normally .

official ArcGIS JS Accessor class

Implementing Accessor | Overview | ArcGIS API for JavaScript 4.24 | ArcGIS Developers