MV - Battle sprites face a specific way!

/*:
 * @target MV MZ
 * @plugindesc v2 - mirror actor battlers when they are in the right-hand half of the screen.
 * @author Caethyril
 * @url https://forums.rpgmakerweb.com/threads/156765/
 * @help Free to use and/or modify for any project, no credit required.
 */
void (function(alias) {
'use strict';
  Sprite_Actor.prototype.updateMain = function() {
    alias.apply(this, arguments);
    const isOnRight = this._homeX > Graphics.boxWidth / 2;
    if (isOnRight === !this._flippedX) {
      this.scale.x *= -1;
      this._flippedX = !this._flippedX;
    }
  };
})(Sprite_Actor.prototype.updateMain);

/*:
 * @target MV MZ
 * @plugindesc v3 - mirror actor battlers when they are in the left-hand half of the screen.
 * @author Caethyril
 * @url https://forums.rpgmakerweb.com/threads/156765/
 * @help Free to use and/or modify for any project, no credit required.
 */
void (function(alias) {
'use strict';
  Sprite_Actor.prototype.updateMain = function() {
    alias.apply(this, arguments);
    const isOnLeft = this._homeX < Graphics.boxWidth / 2;
    if (isOnLeft === !this._flippedX) {
      this.scale.x *= -1;
      this._flippedX = !this._flippedX;
    }
  };
})(Sprite_Actor.prototype.updateMain);

/*:
 * @target MV MZ
 * @plugindesc v4 - mirror actor battlers when they are in the left-hand half of the screen.
 * @author Caethyril
 * @url https://forums.rpgmakerweb.com/threads/156765/
 * @orderAfter YEP_BattleEngineCore
 * @help If using YEP_BattleEngineCore, load this plugin after Yanfly's.
 * 
 * Free to use and/or modify for any project, no credit required.
 */
void (function() {
'use strict';

  /**
   * @param {Sprite_Actor} sprite reference actor sprite.
   * @returns {boolean} `true` iff this plugin should flip `sprite`.
   */
  const shouldActorBeFlipped = function(sprite) {
    const faceFront = !sprite._faceBack;
    const isOnLeft  = sprite._homeX < Graphics.boxWidth / 2;
    return faceFront === isOnLeft;
  };

  // Flip sprites when appropriate.
  void (function() {
    const alias = Sprite_Actor.prototype.updateMain;
    Sprite_Actor.prototype.updateMain = function() {
      alias.apply(this, arguments);
      if (shouldActorBeFlipped(this) === !this._flippedX) {
        this.scale.x *= -1;
        this._flippedX = !this._flippedX;
      }
    };
  })();

  // YEP Battle Engine Core compatibility.
  void (function() { if (!Imported.YEP_BattleEngineCore) return;
    const alias_f = Game_Battler.prototype.spriteFaceForward;
    Game_Battler.prototype.spriteFaceForward = function() {
      alias_f.apply(this, arguments);
      delete this.battler()._faceBack;
    };
    const alias_b = Game_Battler.prototype.spriteFaceBackward;
    Game_Battler.prototype.spriteFaceBackward = function() {
      alias_b.apply(this, arguments);
      this.battler()._faceBack = true;
    };
  })();

})();

/*:
 * @target MV MZ
 * @plugindesc v5 - mirror actor battlers when they are in the left-hand half of the screen.
 * @author Caethyril
 * @url https://forums.rpgmakerweb.com/threads/156765/
 * @orderAfter YEP_BattleEngineCore
 * @help Should be loaded after YEP_BattleEngineCore.
 * 
 * Free to use and/or modify for any project, no credit required.
 */
void (function() {
'use strict';

  // Require YEP Battle Engine Core.
  if (!Imported.YEP_BattleEngineCore)
    throw new Error(
      "This plugin should be loaded after YEP_BattleEngineCore.\nPress F12 for details."
    );

  // Anti-mirror when on left.
  void (function() {
    const alias = Game_Battler.prototype.setMirror;
    Game_Actor.prototype.setMirror = function(value) {
      alias.call(this, value !== this.battler()._homeX < Graphics.boxWidth / 2);
    };
  })();

  // Face "forward" on battle start.
  void (function() {
    const alias = Game_Battler.prototype.onBattleStart;
    Game_Actor.prototype.onBattleStart = function() {
      this.spriteFaceForward();
      alias.apply(this, arguments);
    };
  })();

})();