I have a question about this class in JavaScript. I am a newbie of JavaScript, as normally, we are using new for new object of class, but I see in here that they using var.

For example, from Eloquent Javascript:

var Level = class Level {
  constructor(plan) {
    let rows = plan.trim().split("\n").map(l => [...l]);
    this.height = rows.length;
    this.width = rows[0].length;
    this.startActors = [];
    this.rows = rows.map((row, y) => {
      return row.map((ch, x) => {
        let type = levelChars[ch];
        if (typeof type == "string") return type;
        this.startActors.push(
          type.create(new Vec(x, y), ch));
        return "empty";
      });
    });
  }
}