invoke function from js-constructors.js

js-constructors.js

/**
 * @method invoke
 *
 * Allows the spellcaster to cast spells.
 * The first parameter should either be a `Spell` or `DamageSpell`.
 * If it is a `DamageSpell`, the second parameter should be a `Spellcaster`.
 * The function should return `false` if the above conditions are not satisfied.
 *
 * You should use `instanceof` to check for these conditions.
 *
 * https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/instanceof
 *
 * Next check if the spellcaster has enough mana to cast the spell.
 * If it can cast a spell, it should lose mana  equal to the spell's cost.
 * If there is not enough mana, return `false`.
 *
 * If there is enough mana to cast the spell, return `true`.
 * In addition, if it is a `DamageSpell` reduce the target's health by the spell's damage value.
 *
 * Use functions you've previously created: (`inflictDamage`, `spendMana`)
 * to help you with this.
 *
 * @param  {(Spell|DamageSpell)} spell  The spell to be cast.
 * @param  {Spellcaster} target         The spell target to be inflicted.
 * @return {boolean}                    Whether the spell was successfully cast.
 */
Spellcaster.prototype.invoke = function(spell, target) {
  if ( spell instanceof Spell ) {
    if ( this.mana >= spell.cost ) {
      if ( spell instanceof DamageSpell ) {
        if ( target instanceof Spellcaster ) {
          target.inflictDamage( spell.damage )
        } else {
          return false;
        }
      }
      return this.spendMana(spell.cost);
    } else {
      return false;
    }
  } else {
    return false;
  }
};