如何識別 javascript object 字段的類型，它是一個數組<{}>

Question

我有 JavaScript object 來自可能包含嵌套字段的請求，我需要識別字段類型為 Array<{}> 並且我需要單獨迭代該字段，但在 ZDE9B9ED78D7E2E19DCEEFFEE780E2 中無法實現。 任何人都請建議我根據字段類型查找字段的解決方案。

樣品 object

const obj = {
name:'jane', 
age: 22,
interested_books:[{book_name:'xxx', author_name:'yyy'}, {book_name:'aaa', author_name:'zzz'}],
hobbies:['reading', 'football'],
address:{street_name:'dace street', door_no:12}
}

在這些字段中，我需要迭代 Array<{}> 的字段（即interested_books）

Answer 1

使用isArray檢查 value 是否為數組

 const obj = { name: 'jane', age: 22, interested_books: [{ book_name: 'xxx', author_name: 'yyy' }, { book_name: 'aaa', author_name: 'zzz' }], hobbies: ['reading', 'football'], address: { street_name: 'dace street', door_no: 12 } } for (let keys in obj) { if (Array.isArray(obj[keys])) { obj[keys].forEach(item => console.log(item)) } }

Answer 2

使用Object.entires()和isArray來檢查它是否是一個數組

 obj = { name: "jane", age: 22, interested_books: [ { book_name: "xxx", author_name: "yyy" }, { book_name: "aaa", author_name: "zzz" }, ], hobbies: ["reading", "football"], address: { street_name: "dace street", door_no: 12 }, }; function getArrWithOb(obj) { return Object.fromEntries( Object.entries(obj).filter((o) => { if (Array.isArray(o[1])) { if (o[1].every((ob) => typeof ob == "object")) { return o; } } }) ); } console.log(getArrWithOb(obj));

從評論看來，您想要返回的是屬性的名稱您可以使用reduce

 obj = { name: "jane", age: 22, interested_books: [ { book_name: "xxx", author_name: "yyy" }, { book_name: "aaa", author_name: "zzz" }, ], hobbies: ["reading", "football"], address: { street_name: "dace street", door_no: 12 }, }; function getArrWithOb(obj) { return Object.entries(obj).reduce((r, o) => { if (Array.isArray(o[1])) { if (o[1].every((ob) => typeof ob == "object")) { r.push(o[0]); } } return r; }, []); } console.log(getArrWithOb(obj));

Answer 3

您也可以使用instanceof

 const obj = { name:'jane', age: 22, interested_books:[{book_name:'xxx', author_name:'yyy'}, {book_name:'aaa', author_name:'zzz'}], hobbies:['reading', 'football'], address:{street_name:'dace street', door_no:12} } for (const v in obj) obj[v] instanceof Array && console.log(obj[v]);

Answer 4

 const obj = { name: 'jane', age: 22, interested_books: [{ book_name: 'xxx', author_name: 'yyy' }, { book_name: 'aaa', author_name: 'zzz' }], hobbies: ['reading', 'football'], address: { street_name: 'dace street', door_no: 12 } } for (const key in obj) { if (obj[key] instanceof Array) { console.log('I am array', key); const isArrayOfObject = obj[key].every(item => typeof item === "object"); if (isArrayOfObject) { // your_logic_here } } }

Answer 5

試試下面的 function。 這是為了獲取 object 中的項目，即 arrays。

const obj = {
  name: 'jane',
  age: 22,
  interested_books: [{ book_name: 'xxx', author_name: 'yyy' }, { book_name: 'aaa', author_name: 'zzz' }],
  hobbies: ['reading', 'football'],
  address: { street_name: 'dace street', door_no: 12 }
};

const getArraysFromObject = obj => {
  const results = {};
  Object.keys(obj).map(field => {
    if (Array.isArray(obj[field])) {
      results[field] = obj[field];
    }
  });
  return results;
};

console.log(results); 
// {
//   "interested_books": [
//     { "book_name": "xxx", "author_name": "yyy" },
//     { "book_name": "aaa", "author_name": "zzz" }
//   ],
//   "hobbies": ["reading", "football"]
// }

Answer 6

您可以使用typeof檢查 value 是否為數組

 const obj = { name:'jane', age: 22, interested_books:[{book_name:'xxx', author_name:'yyy'}, {book_name:'aaa', author_name:'zzz'}], hobbies:['reading', 'football'], address:{street_name:'dace street', door_no:12} } for (x in obj) { txt = obj[x]; if(typeof(txt) == "object") { for(oj in txt) { ojval = txt[oj]; console.log(ojval); } } }