Question

我正在尝试创建一个从对象返回所需属性的函数。

对象将如下所示：

export var Characters = [
    {
        id: 1,
        Name: "Abe",
        HitPointValue: "124",
        StrengthValue: "12",
        IntelligenceValue: "14",
        WisdomValue: "16",
        DexterityValue: "12",
        ConstitutionValue: "10",
        CharismaValue: "17",
        Avatar: require('./images/avatar_7.jpg')
    }
]

我试过了：

export function getStat(id, stat) {
    var idx = Characters.findIndex((val) => val.id == id);
    return Characters[idx].stat;
}

例如，假设我需要获得此对象的“WisdomValue”。

所以我称之为：

        <Text style={[styles.stats]}>
            {"\n"}
            Wisdom Value: {getStat(1, 'WisdomValue')}{"\n"}
        </Text>

但我只是得到一个错误'undefined is not object'

如何才能获得一个特定属性，但是以动态方式？所以我不必编写像getHitPointValue（id）这样的separte函数，获取StrengthValue（id）等等......

谢谢！

Answer 1

使用[]而不是使用点表示法，因为您尝试通过动态键访问值。

检查此代码段：

＆＃13;

var Characters = [
    {
        id: 1,
        Name: "Abe",
        HitPointValue: "124",
        StrengthValue: "12",
        IntelligenceValue: "14",
        WisdomValue: "16",
        DexterityValue: "12",
        ConstitutionValue: "10",
        CharismaValue: "17",
    }
]

function getStat(id, stat) {
    var idx = Characters.findIndex((val) => val.id == id);
    if(idx >= 0)
       return Characters[idx][stat];
    else return "not found"
}

console.log(getStat(1, 'WisdomValue'));
console.log(getStat('15', 'abc'));

＆＃13;

Answer 2

＆＃13;

var Characters = [
    {
        id: 1,
        Name: "Abe",
        HitPointValue: "124",
        StrengthValue: "12",
        IntelligenceValue: "14",
        WisdomValue: "16",
        DexterityValue: "12",
        ConstitutionValue: "10",
        CharismaValue: "17",
    }
]

function getStat(id, stat) {
    // you can directly find the object rather going through the array index
    var character = Characters.find((val) => val.id == id);
    // care for non existing characters
    if (!character) {
        throw new Error(`Character with id ${id} does not exist`);
    }
    // care for non existing stats
    if (!character.hasOwnProperty(stat)) {
        throw new Error(`Stat ${stat} is not available for character with id ${id}`);
    }
    // use the [] notation as opposed to the dot notation when evaluating dynamic property names
    return character[stat];
}

console.log(`Wisdom Value: ${getStat(1, 'WisdomValue')}`);
console.log(`Charisma Value: ${getStat(1, 'CharismaValue')}`);

try {
    console.log(getStat(2, 'Name'));
} catch (e) {
    console.log(e.message);
}

try {
    console.log(getStat(1, 'PersuasionValue'));
} catch (e) {
    console.log(e.message);
}

＆＃13;

动态返回对象的特定属性

2 个答案: