无法减少数组中的相关 JavaScript 对象

Question

我正在尝试将相关的 JavaScript 对象按键分组到一个数组中。

但是，我被困在了一个点上。

我有一个类似这样的 JavaScript 对象数组：

[
    {
        "text": "hello world",
        "startPos": 0,
        "endPos": 12,
        "value": "hello world",
        "entity": "Greeting"
    },
    {
        "text": "hello world",
        "startPos": 0,
        "endPos": 6,
        "value": "hello",
        "entity": "Greeting"
    }
]

我编写了以下代码，但我被卡住了。

a = [
  {
    "text": "hello world",
    "startPos": 0,
    "endPos": 12,
    "value": "hello world",
    "entity": "Greeting"
  },
  {
    "text": "hello world",
    "startPos": 0,
    "endPos": 6,
    "value": "hello",
    "entity": "Greeting"
  }
]

let result = a.reduce((acc, d) => {
  const found = acc.find(a => a.text == d.text);
  const entitiesArray = {
    startPos: d.startPos,
    endPos: d.endPos,
    entity: d.entity
  };
  if (found) {
    found.entities.push(entitiesArray);
  } else {
    acc.push({});
  }
  return acc;
}, []);

console.log(JSON.stringify(result, undefined, 4));

JavaScript 对象根据"text" 键重复。我想根据"text" 键将上述数组组合成一个对象。

类似这样的：

[
    {
        "text": "hello world",
        "entities": [
                {
                    "startPos": 0,
                    "endPos": 12,
                    "value": "hello world",
                    "entity": "Greeting"
                },
                {
                    "startPos": 0,
                    "endPos": 6,
                    "value": "hello",
                    "entity": "Greeting"
                }
        ]
    }
]

Answer 1

当found 为假时，您错过了将带有text 的对象添加到数组中。所以在接下来的迭代中，它无法找到比较它们的文本的对象

另外，如果你的 IDE 和引擎支持新的 ES 提案，你可以使用Rest/Spread Properties

const a = [
  {
    "text": "hello world",
    "startPos": 0,
    "endPos": 12,
    "value": "hello world",
    "entity": "Greeting"
  },
  {
    "text": "hello world",
    "startPos": 0,
    "endPos": 6,
    "value": "hello",
    "entity": "Greeting"
  }
]

let result = a.reduce((acc, d) => {
  const found = acc.find(a => a.text == d.text);
  
  const { text, ...entitiesArray } = { ...d }; // <- Rest/Spread properties
  
  found ? found.entities.push(entitiesArray) 
        : acc.push({ text: d.text, entities: [entitiesArray]})

  return acc;
}, []);

console.log(result);

Answer 2

您还可以使用reduce 和Object.values 制作更短的版本

let a = [{
    "text": "hello world",
    "startPos": 0,
    "endPos": 12,
    "value": "hello world",
    "entity": "Greeting"
  },
  {
    "text": "hello world",
    "startPos": 0,
    "endPos": 6,
    "value": "hello",
    "entity": "Greeting"
  }
];

let result = Object.values(a.reduce((c, v) => {
  c[v.text] = c[v.text] || {text: v.text,entities: []};
  c[v.text].entities.push(v);
  return c;
}, {}));

console.log(result);

---

没有text 属性

let a = [{
    "text": "hello world",
    "startPos": 0,
    "endPos": 12,
    "value": "hello world",
    "entity": "Greeting"
  },
  {
    "text": "hello world",
    "startPos": 0,
    "endPos": 6,
    "value": "hello",
    "entity": "Greeting"
  }
];

let result = Object.values(a.reduce((c, v) => {
  let {text: _,...o} = v;
  c[v.text] = c[v.text] || {text: v.text,entities: []};
  c[v.text].entities.push(o);
  return c;
}, {}));

console.log(result);

Answer 3

您可以为实体添加一个带有文本的新对象和一个数组。

此解决方案采用已破坏的对象并使用键构建新对象。

var a = [{ text: "hello world", startPos: 0, endPos: 12, value: "hello world", entity: "Greeting" }, { text: "hello world", startPos: 0, endPos: 6, value: "hello", entity: "Greeting" }],
    result = a.reduce((acc, { text, startPos, endPos, entity, value }) => {
        var found = acc.find(a => a.text === text),
            subEntity = { startPos, endPos, entity, value };

        if (found) {
            found.entities.push(subEntity);
        } else {
            acc.push({ text, entities: [subEntity] });
        }
        return acc;
    }, []);

console.log(result);

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rest parameters ... 用于destructuring 属性和BABEL。

var a = [{ text: "hello world", startPos: 0, endPos: 12, value: "hello world", entity: "Greeting" }, { text: "hello world", startPos: 0, endPos: 6, value: "hello", entity: "Greeting" }],
    result = a.reduce((acc, { text, ...subEntity }) => {
        var found = acc.find(a => a.text === text);

        if (found) {
            found.entities.push(subEntity);
        } else {
            acc.push({ text, entities: [subEntity] });
        }
        return acc;
    }, []);

console.log(result);

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