如何访问对象的值？

Question

我正在尝试遍历一组对象并获取第一个值（品种）。喜欢：

比格犬

金毛猎犬

柯基犬

金嘟嘟

拉布拉多猎犬

现在我映射了数据，但它只列出了每个 {}。我如何访问每个 {} 内部？

const data = [

    { 

        "breed": "Beagle",

        "characteristics": "playful" 

    },

    {

        "breed": "Golden Retriever", 

        "characteristics": "calm" 

    },

    {

        "breed": "Corgi", 

        "characteristics": "bright" 

    },

    {

        "breed": "Goldendoodle", 

        "characteristics": "gentle" 

    },

    {

        "breed": "Labrador Retriever", 

        "characteristics": "loyal" 

    },

]

data.map(item => {

    console.log(item);

})

// Object { breed: "Beagle", characteristics: "playful" }, Object { breed: "Golden Retriever", characteristics: "calm" }, ...

Answer 1

要获取品种，请breed从每个项目中提取。const data = [{"breed":"Beagle","characteristics":"playful"},{"breed":"Golden Retriever","characteristics":"calm"},{"breed":"Corgi","characteristics":"bright"},{"breed":"Goldendoodle","characteristics":"gentle"},{"breed":"Labrador Retriever","characteristics":"loyal"}];const res = data.map(({ breed }) => breed);console.log(res);ES5 语法：var data = [{"breed":"Beagle","characteristics":"playful"},{"breed":"Golden Retriever","characteristics":"calm"},{"breed":"Corgi","characteristics":"bright"},{"breed":"Goldendoodle","characteristics":"gentle"},{"breed":"Labrador Retriever","characteristics":"loyal"}];var res = data.map(function(item) {  return item.breed});console.log(res);如果您只想记录每个项目，请使用forEach循环：const data = [{"breed":"Beagle","characteristics":"playful"},{"breed":"Golden Retriever","characteristics":"calm"},{"breed":"Corgi","characteristics":"bright"},{"breed":"Goldendoodle","characteristics":"gentle"},{"breed":"Labrador Retriever","characteristics":"loyal"}];data.forEach(({ breed }) => console.log(breed));

Answer 2

简单地：data.map(item => {    console.log(item.breed);})