如何在本机反应中使用for循环遍历数组？

Question

我正在尝试在本机反应中循环 json 数据。我想创建一个具有不同 key 和 values 的新数组将是循环的 json 结果。我尝试了以下方法，但没有任何效果预期。json响应的格式如下。

json

 0: {key: 0, id: 0, type: "section", title: "A1. India's Economic Development", duration: 0, …}
    1: {key: 1, id: "1", type: "unit", title: "1. India as a Developing Economy", duration: 0, …}
    2: {key: 2, id: "2", type: "unit", title: "2. Understanding India’s economic transition", duration: 0, …}
    3: {key: 17, id: 0, type: "section", title: "A2. National Income", duration: 0, …}
    4: {key: 18, id: "5", type: "unit", title: "1. India in the global economy", duration: 0, …}
    5: {key: 19, id: "6", type: "unit", title: "2. China, India and the rise of Asia", duration: 0, …}

我想要一个这样的数组

const dataArray = [
  {
    title: "India's Economic Development",
    content:
      "India as a Developing Economy",
      "Understanding India’s economic transition"

  },
  {
    title: "National Income",
    content:
      "India in the global economy",
      "China, India and the rise of Asia"
  }
]

以下是我已经完成的循环，但没有任何内容。请帮助

.then((response) => response.json())
.then((responseData) => {

    responseData.map(detail => {

        let resultk = [];
        //console.log( detail.data.curriculum);
        for (var i = 0, j = 0; i < detail.data.curriculum.length; i++) {
            curr = detail.data.curriculum;
            console.log(curr.title);
            if (curr.type === "section") {
                resultk['title'] = curr.title;
                this.result[j++] = resultk;

            } else if (curr.type === "unit") {
                resultk['content'] = curr.title;
            }
        }
        console.log(resultk)
    })
})

Answer 1

const resp = [
    {key: 0, id: 0, type: "section", title: "A1. India's Economic Development", duration: 0},
    {key: 1, id: "1", type: "unit", title: "1. India as a Developing Economy", duration: 0},
    {key: 2, id: "2", type: "unit", title: "2. Understanding India’s economic transition", duration: 0},
    {key: 17, id: 0, type: "section", title: "A2. National Income", duration: 0},
    {key: 18, id: "5", type: "unit", title: "1. India in the global economy", duration: 0},
    {key: 19, id: "6", type: "unit", title: "2. China, India and the rise of Asia", duration: 0},
]

如果 resp 是一个长度和 0, 1, 2, ... 键的对象，使用 Array.from(obj) 将其转换为一个对象

如果resp被排序（每个单元属于上一节）

const result = []
resp.forEach(item => {
    if (item.type === 'section') { // create a new collection
        result.push({
            title: item.title,
            content: []
        })
    } else if (item.type === 'unit') {
        if (result.length === 0) throw new Error('No section specified yet')
        result[result.length - 1].content.push(item.title)
    } else {
        throw new TypeError('Invalid data type')
    }
})

要从标题中删除第一个单词，请使用

function removeFirstWord(str) {
    return str.replace(/^[^\s]+\s/, '')
}

/symbols/这个东西叫做正则表达式

• 字符串以（第一个 ^ 符号）除 a 以外的任何字符开始
• 空白（空白=\s，[^something] 表示不是某事）
• 加号表示最后一部分可以重复 1 次或多次

到目前为止，它找到了第一个单词

• \s 表示也替换单词后的空格

Answer 2

使用reduce函数和一个变量来跟踪累加器数组的索引

检查它的类型是section，然后在累加器数组中推送值并将变量值更新1。

如果类型是单位，则在内容中添加由currIndex变量定义的索引处的值

let value = [{
    key: 0,
    id: 0,
    type: "section",
    title: "A1. India's Economic Development",
    duration: 0
  },
  {
    key: 1,
    id: "1",
    type: "unit",
    title: "1. India as a Developing Economy",
    duration: 0
  },
  {
    key: 2,
    id: "2",
    type: "unit",
    title: "2. Understanding India’s economic transition",
    duration: 0
  },
  {
    key: 17,
    id: 0,
    type: "section",
    title: "A2. National Income",
    duration: 0
  },
  {
    key: 18,
    id: "5",
    type: "unit",
    title: "1. India in the global economy",
    duration: 0
  },
  {
    key: 19,
    id: "6",
    type: "unit",
    title: "2. China, India and the rise of Asia",
    duration: 0
  }
]

let currIndex = -1;
let k = value.reduce((acc, curr) => {

  if (curr.type === 'section') {
    acc.push({
      title: curr.title.split('.')[1].trim(),
      content: []
    })
    currIndex += 1
  } else {
    acc[currIndex].content.push(curr.title)
  }

  return acc;


}, []);
console.log(k)

Answer 3

这是你想要的完整示例代码，尝试使用最终循环更改数据，你会得到你想要的输出：

testingggg = () => {
    var data = {
        0: {key: 0, id: 0, type: "section", title: "A1. India's Economic Development", duration: 0},
        1: {key: 1, id: "1", type: "unit", title: "1. India as a Developing Economy", duration: 0},
        2: {key: 2, id: "2", type: "unit", title: "2. Understanding India’s economic transition", duration: 0},
        3: {key: 17, id: 0, type: "section", title: "A2. National Income", duration: 0},
        4: {key: 18, id: "5", type: "unit", title: "1. India in the global economy", duration: 0},
        5: {key: 19, id: "6", type: "unit", title: "2. China, India and the rise of Asia", duration: 0}
    }

    var keys = [];
    for(var k in data) keys.push(k);

    //alert("total " + keys.length + " keys: " + keys);

    var dataArray = [] 

    for(i=0;i<keys.length;i++)
    {
        var newObj = { // Change your required detail here
            type: data[i].type,
            title: data[i].title
        }
        dataArray.push(newObj);
    }
    console.log(dataArray);
}

Answer 4

这是一种可能的解决方案。如果我正确理解了这个问题，您想重新格式化并将该部分组合为标题，将单元组合为内容......

var data = {
    0: { key: 0, id: 0, type: "section", title: "A1. India's Economic Development", duration: 0 },
    1: { key: 1, id: "1", type: "unit", title: "1. India as a Developing Economy", duration: 0 },
    2: { key: 2, id: "2", type: "unit", title: "2. Understanding India’s economic transition", duration: 0 },
    3: { key: 17, id: 0, type: "section", title: "A2. National Income", duration: 0 },
    4: { key: 18, id: "5", type: "unit", title: "1. India in the global economy", duration: 0 },
    5: { key: 19, id: "6", type: "unit", title: "2. China, India and the rise of Asia", duration: 0 }
};

var keys = Object.keys(data);

var dataArray = [];
var push = true;
var toPush = null;

for (var i = 0; i < keys.length; i++) {

    var key = keys[i];
    var obj = data[key];

    switch (obj.type) {
        case "section":
            if (toPush !== null) {
                dataArray.push({ ...toPush });
            }
            toPush = {};
            var titleText = obj.title.split(".")[1].trim();//if there is always a "." in the title string this will clean that up;
            toPush.title ? toPush.title += `, ${titleText}` : toPush.title = titleText;
            push = true;
            break;
        case "unit":
            push = false;
            var contentText = obj.title.split(".")[1].trim();//if there is always a "." in the title string this will clean that up;
            toPush.content ? toPush.content += `, ${contentText}` : toPush.content = contentText;
            break;
        default: break;
    }
}

//push the last one
dataArray.push({ ...toPush });

console.log(JSON.stringify(dataArray, null, 2));

//result =>
[
  {
    "title": "India's Economic Development",
    "content": "India as a Developing Economy, Understanding India’s economic transition"
  },
  {
    "title": "National Income",
    "content": "India in the global economy, China, India and the rise of Asia"
  }
]