How to use Phaser.Group.forEach

gistfile1.js

create: function () {
  var offsetX = 120; // offset from the screen border
  var offsetY = 30;
  var margin = 10; // margin between enemies
  var rows = 4;
  var cols = 6;
  
  // loop for using the offset and margin variables
  this.enemies = game.add.group();
  for (i = 0; i < rows; i++) {
    for (j = 0; j < cols = j++) {
      var ship = this.enemies.create(0, 0, img);
      ship.x = ship.width * j + margin + offsetX;
      ship.y = ship.height * i + margin + offsetY;
    }
  }
},

update: function () {
  // how to call the forEach function
  this.enemies.forEach(this.moveEnemy, this);
},

// the function to be called for each element in the group
moveEnemy: function (enemy) {
  var speed = 10;
  enemy.x += game.time.physicsElapsed * speed;
}