How to efficiently filter elements of a specific status value in a JSON nested array?

Efficient filtering of JSON nested arrays: precisely locate specific status values

When processing JSON data, it is often necessary to extract data that meets specific conditions from nested arrays. This article demonstrates how to accurately filter out elements with status values ​​0 and 1 from JSON data containing nested arrays.

Sample JSON data:

 const data = [
  { "id": 1, "name": "alice", age: [{ id: 4, status: 0 }] },
  { "id": 2, "name": "bob", age: [{ id: 4, status: 1 }] },
  { "id": 3, "name": "charlie", age: [{ id: 4, status: 1 }] }
];

The goal is to filter out objects in the age array with status 0 and status 1 from the data array respectively.

JavaScript's filter() and some() methods can achieve this. filter() creates a new array containing elements passing the test; some() tests whether at least one element in the array passes the test.

First, filter elements with status 0:

 const status0 = data.filter(item => item.age.some(a => a.status === 0));
console.log(status0);

filter() iterates over each object in the data array. For each object, some() checks whether there is an element with status 0 in its age array. If present, the object is added to status0 array.

Next, filter the element with status 1:

 const status1 = data.filter(item => item.age.some(a => a.status === 1));
console.log(status1);

This code is similar to filtering for a code with status 0, only replacing a.status === 0 with a.status === 1 .

If age array may contain multiple elements and need to filter out objects with status 0 or 1 in age array, and remove elements that do not meet the conditions in age array, more complex processing is required:

 const data = [
  { "id": 1, "name": "Alice", age: [{ id: 4, status: 0 }, { id: 5, status: 1 }] },
  { "id": 2, "name": "Bob", age: [{ id: 4, status: 1 }, { id: 5, status: 2 }] },
  { "id": 3, "name": "Charlie", age: [{ id: 4, status: 1 }, { id: 5, status: 3 }] }
];

const status0 = data.map(item => ({
  ...item,
  age: item.age.filter(a => a.status === 0)
})).filter(item => item.age.length > 0);

console.log(status0);

const status1 = data.map(item => ({
  ...item,
  age: item.age.filter(a => a.status === 1)
})).filter(item => item.age.length > 0);

console.log(status1);

This code uses map() method to process each object. filter() method filters out elements that meet the conditions in the age array, and uses filter() method to filter out objects whose age array is empty.

Through these methods, the required data collection can be extracted from JSON data efficiently.

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