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);

})