Why is converting an array to an object important in some situations?

Understand the importance of converting arrays to objects: Practical examples Converting arrays to objects has the following benefits: Convenient access to data: Object properties can be accessed through dots or square brackets, which is more intuitive than array indexing. Find duplicates: Object key values ​​are unique and duplicates will be merged into a single attribute value. Group data: Data can be grouped based on specific attributes to improve search speed.

Understand the importance of converting arrays to objects: practical cases

In JavaScript, arrays and objects are two common types of data type. Sometimes it is necessary to convert an array into an object to meet specific needs. This article explores the reasons for converting an array into an object and how to do it with code examples.

Reason 1: Easy access

Array elements can only be accessed through indexes, while object properties can be accessed through dots or square brackets. Converting arrays into objects makes accessing data more convenient and intuitive.

// 数组
const names = ["John", "Jane", "Bob"];

// 转换成对象
const namesObj = {0: "John", 1: "Jane", 2: "Bob"};

console.log(names[1]); // 'Jane'
console.log(namesObj.1); // 'Jane'

Reason 2: Find duplicates

Convert the array into an object to easily find duplicates. The keys for attributes within an object are unique, so if there are duplicates they will be merged into one attribute value.

// 数组
const numbers = [1, 2, 3, 1, 4, 5, 2];

// 转换成对象
const numbersObj = Object.assign({}, numbers);

console.log(Object.keys(numbersObj)); // [ '0', '1', '2', '3', '4', '5' ]

Reason 3: Grouping data

Converting an array into an object can group data based on certain attributes. This object can be used as a hash table to improve lookup speed.

// 数组
const students = [
  { name: "John", grade: 90 },
  { name: "Jane", grade: 85 },
  { name: "Bob", grade: 95 },
];

// 基于年级分组
const studentsByGrade = students.reduce((obj, student) => {
  if (!obj[student.grade]) {
    obj[student.grade] = [];
  }
  obj[student.grade].push(student);
  return obj;
}, {});

console.log(studentsByGrade);
/*
{
  90: [{ name: 'John', grade: 90 }],
  85: [{ name: 'Jane', grade: 85 }],
  95: [{ name: 'Bob', grade: 95 }]
}
*/

Notes

• The complexity of converting an array into an object is O(n), where n is the length of the array.
• When you create a new object using the Object.assign method, a shallow copy is created. If the object contains complex data structures (such as nested arrays or objects), changing it will also affect the original array.

Conclusion

Array to object is very useful in specific situations, such as easy access, finding duplicates and grouping data. By understanding these reasons and associated code examples, developers can effectively leverage this transformation to improve program efficiency and code readability.

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