pokemon types multipliers

log.js

console.log(getMultipliers(['poison','fire']))

type-multiplier.js

function getMultipliers(types) {
    var multipliers = {
        defense: {},
        attack: {}
    }
    types.forEach( (type) => {
        var damage_relations = all_types[type]
        var no_damage_to = damage_relations.attack.zero
        var no_damage_from = damage_relations.defense.zero
        var half_damage_to = damage_relations.attack.half
        var half_damage_from = damage_relations.defense.half
        var double_damage_to = damage_relations.attack.double
        var double_damage_from = damage_relations.defense.double
        no_damage_to.forEach((type) => {
          if(multipliers.attack.hasOwnProperty(type)){multipliers.attack[type] = multipliers.attack[type] * 0}
          else{multipliers.attack[type] = 0}
        })
        no_damage_from.forEach((type) => {
          if(multipliers.defense.hasOwnProperty(type)){multipliers.defense[type] = multipliers.defense[type] * 0}
          else{multipliers.defense[type] = 0}
        })
        half_damage_to.forEach((type) => {
          if(multipliers.attack.hasOwnProperty(type)){multipliers.attack[type] = multipliers.attack[type] * 0.5}
          else{multipliers.attack[type] = 0.5}
        })
        half_damage_from.forEach((type) => {
          if(multipliers.defense.hasOwnProperty(type)){multipliers.defense[type] = multipliers.defense[type] * 0.5}
          else{multipliers.defense[type] = 0.5}
        })
        double_damage_to.forEach((type) => {
          if(multipliers.attack.hasOwnProperty(type)){multipliers.attack[type] = multipliers.attack[type] * 2}
          else{multipliers.attack[type] = 2}
        })
        double_damage_from.forEach((type) => {
          if(multipliers.defense.hasOwnProperty(type)){multipliers.defense[type] = multipliers.defense[type] * 2}
          else{multipliers.defense[type] = 2}
        })
    })
    return multipliers
}

types.js

var all_types = {
    bug: {
        attack: {
            double: ['psychic', 'grass', 'dark'],
            half: ['fighting', 'fire', 'flying', 'ghost', 'poison', 'steel', 'fairy'],
            zero: []
        },
        defense: {
            half: ['fighting', 'grass', 'ground'],
            double: ['fire', 'flying', 'rock'],
            zero: []
        }
    },
    dark: {
        attack: {
            double: ['ghost', 'psychic'],
            half: ['dark', 'fighting', 'fairy'],
            zero: []
        },
        defense: {
            half: ['dark', 'ghost'],
            double: ['bug', 'fighting', 'fairy'],
            zero: ['psychic']
        }
    },
    dragon: {
        attack: {
            double: ['dragon'],
            half: ['steel'],
            zero: ['fairy']
        },
        defense: {
            half: ['electric', 'fire', 'grass', 'water'],
            double: ['dragon', 'ice', 'fairy'],
            zero: []
        }
    },
    electric: {
        attack: {
            double: ['flying', 'water'],
            half: ['dragon', 'electric', 'grass'],
            zero: ['ground']
        },
        defense: {
            half: ['electric', 'flying', 'steel'],
            double: ['ground'],
            zero: []
        }
    },
    fairy: {
        attack: {
            double: ['dark', 'dragon', 'fighting'],
            half: ['fire', 'poison', 'steel'],
            zero: []
        },
        defense: {
            half: ['bug', 'dark', 'fighting'],
            double: ['poison', 'steel'],
            zero: ['dragon']
        }
    },
    fighting: {
        attack: {
            double: ['dark', 'ice', 'normal', 'rock', 'steel'],
            half: ['bug', 'fairy', 'flying', 'poison', 'psychic'],
            zero: ['ghost']
        },
        defense: {
            half: ['bug', 'dark', 'rock'],
            double: ['fairy', 'flying', 'psychic'],
            zero: []
        }
    },
    fire: {
        attack: {
            double: ['bug', 'grass', 'ice', 'steel'],
            half: ['dragon', 'fire', 'rock', 'water'],
            zero: []
        },
        defense: {
            half: ['bug', 'fairy', 'fire', 'grass', 'ice', 'steel'],
            double: ['bug', 'fire', 'flying', 'ice', 'poison'],
            zero: []
        }
    },
    flying: {
        attack: {
            double: ['bug', 'fighting', 'grass'],
            half: ['electric', 'rock', 'steel'],
            zero: []
        },
        defense: {
            half: ['bug', 'fighting', 'grass'],
            double: ['electric', 'ice', 'rock'],
            zero: ['ground']
        }
    },
    ghost: {
        attack: {
            double: ['ghost', 'psychic'],
            half: ['dark'],
            zero: ['normal']
        },
        defense: {
            half: ['bug', 'poison'],
            double: ['ghost', 'dark'],
            zero: ['normal', 'fighting']
        }
    },
    grass: {
        attack: {
            double: ['ground', 'rock', 'water'],
            half: ['bug', 'dragon', 'fire', 'flying', 'grass', 'poison', 'steel'],
            zero: []
        },
        defense: {
            half: ['electric', 'grass', 'ground', 'water'],
            double: ['bug', 'fire', 'flying', 'ice', 'poison'],
            zero: []
        }
    },
    ground: {
        attack: {
            double: ['electric', 'fire', 'poison', 'rock', 'steel'],
            half: ['bug', 'grass'],
            zero: ['flying']
        },
        defense: {
            half: ['poison', 'rock'],
            double: ['grass', 'ice', 'water'],
            zero: ['electric']
        }
    },
    ice: {
        attack: {
            double: ['dragon', 'flying', 'grass', 'ground'],
            half: ['fire', 'ice', 'steel', 'water'],
            zero: []
        },
        defense: {
            half: ['ice'],
            double: ['fighting', 'fire', 'rock', 'steel'],
            zero: []
        }
    },
    normal: {
        attack: {
            double: [],
            half: ['rock', 'steel'],
            zero: ['ghost']
        },
        defense: {
            half: [],
            double: ['fighting'],
            zero: ['ghost']
        }
    },
    poison: {
        attack: {
            double: ['grass', 'fairy'],
            half: ['ghost', 'ground', 'poison', 'rock'],
            zero: ['steel']
        },
        defense: {
            half: ['bug', 'fairy', 'fighting', 'grass', 'poison'],
            double: ['ground', 'psychic'],
            zero: []
        }
    },
    psychic: {
        attack: {
            double: ['fighting', 'poison'],
            half: ['psychic', 'steel'],
            zero: ['dark']
        },
        defense: {
            half: ['fighting', 'psychic'],
            double: ['bug', 'dark', 'ghost'],
            zero: []
        }
    },
    rock: {
        attack: {
            double: ['bug', 'fire', 'flying', 'ice'],
            half: ['fighting', 'ground', 'steel'],
            zero: []
        },
        defense: {
            half: ['fire', 'flying', 'normal', 'poison'],
            double: ['fighting', 'grass', 'ground', 'steel', 'water'],
            zero: []
        }
    },
    steel: {
        attack: {
            double: ['fairy', 'ice', 'rock'],
            half: ['electric', 'fire', 'steel', 'water'],
            zero: []
        },
        defense: {
            half: ['bug', 'dragon', 'fairy', 'flying', 'grass', 'ice', 'normal', 'psychic', 'rock', 'steel'],
            double: ['fighting', 'fire', 'ground'],
            zero: ['poison']
        }
    },
    water: {
        attack: {
            double: ['fire', 'ground', 'rock'],
            half: ['dragon', 'grass', 'steel'],
            zero: []
        },
        defense: {
            half: ['fire', 'ice', 'steel', 'water'],
            double: ['electric', 'grass'],
            zero: []
        }
    }
};