How to use enumeration elegantly in the front end

Enumeration (Enumeration) is a common programming data type, which is used to represent a limited set of values. In front-end development, enumerations can be used to define constants, options, etc., which help to improve the readability and maintainability of the code. This article will introduce how to use enumerations elegantly in the front end.

Definition and use of enumeration

In JavaScript, enumeration is not a native data type, but you can use objects or constants to simulate enumeration. Here's an example of simulating an enum using an object:

const Weekdays = {
  MONDAY: 1,
  TUESDAY: 2,
  WEDNESDAY: 3,
  THURSDAY: 4,
  FRIDAY: 5,
  SATURDAY: 6,
  SUNDAY: 7,
};

In the above code, we use objects to define a set of enumeration values, each enumeration value is a property, corresponding to an integer value. Enumeration values ​​can be accessed in the following ways:

console.log(Weekdays.MONDAY); // 1
console.log(Weekdays.TUESDAY); // 2

In actual development, we can use enumeration values ​​to represent constants, options, etc. For example, the following code demonstrates how to use an enumeration value to represent a set of options:

const Gender = {
  MALE: 'male',
  FEMALE: 'female',
  OTHER: 'other',
};

function renderGenderOptions() {
  const select = document.createElement('select');
  for (const gender in Gender) {
    const option = document.createElement('option');
    option.value = Gender[gender];
    option.textContent = gender;
    select.appendChild(option);
  }
  return select;
}

In the code above, we use an enum value Genderto represent a set of gender options and renderGenderOptions()a function to generate a dropdown menu containing the options.

Elegant use of enums

While mocking enums with objects is a simple and effective way, in practice, we can use enums in some elegant ways.

Use the Symbol type

ES6 introduces a new native data type Symbolthat can be used to define unique property names or constants. Using Symboltypes can make enums more concise and elegant. Here is Symbolan example of defining an enum with a type:

const Weekdays = {
  MONDAY: Symbol('MONDAY'),
  TUESDAY: Symbol('TUESDAY'),
  WEDNESDAY: Symbol('WEDNESDAY'),
  THURSDAY: Symbol('THURSDAY'),
  FRIDAY: Symbol('FRIDAY'),
  SATURDAY: Symbol('SATURDAY'),
  SUNDAY: Symbol('SUNDAY'),
};

In the code above, we use Symboltypes to define a unique set of enum values, each of which is a separate Symbolobject. Enumeration values ​​can be accessed in the following ways:

console.log(Weekdays.MONDAY); // Symbol(MONDAY)
console.log(Weekdays.TUESDAY); // Symbol(TUESDAY)

It can be seen that the enumeration defined using the `Symbol` type is more concise and elegant, and there will be no problem of naming conflicts. However, it should be noted that the enumeration value defined using the `Symbol` type is an independent object, and it cannot be judged whether it is equal by equality comparison, and the `Object.is()` method needs to be used for comparison.

### Use enum class

In object-oriented languages ​​such as Java, an enumeration is a special class that can define constants, methods, etc. In JavaScript, although there is no native enumeration class, enumerations can be simulated through classes. Here's an example of using a class to emulate an enum:

class Weekdays {
  static MONDAY = new Weekdays('MONDAY', 1);
  static TUESDAY = new Weekdays('TUESDAY', 2);
  static WEDNESDAY = new Weekdays('WEDNESDAY', 3);
  static THURSDAY = new Weekdays('THURSDAY', 4);
  static FRIDAY = new Weekdays('FRIDAY', 5);
  static SATURDAY = new Weekdays('SATURDAY', 6);
  static SUNDAY = new Weekdays('SUNDAY', 7);

  constructor(name, value) {
    this.name = name;
    this.value = value;
  }

  toString() {
    return this.name;
  }
}

In the code above, we define a Weekdaysclass to represent a set of days of the week enumeration values. Each enumeration value is an Weekdaysinstance object of a class, which has name and value attributes, and can also define methods, etc. Enumeration values ​​can be accessed in the following ways:

console.log(Weekdays.MONDAY); // Weekdays {name: "MONDAY", value: 1}
console.log(Weekdays.TUESDAY); // Weekdays {name: "TUESDAY", value: 2}

As you can see, using a class to simulate an enumeration can make the code more object-oriented, and at the same time define methods, etc. However, it should be noted that the use of class simulation enumeration may increase the amount of code, which needs to be selected according to the actual situation.

Summarize

Enums are a common programming data type that help improve the readability and maintainability of your code. In front-end development, we can use objects or constants to simulate enumerations, and we can also use ES6 Symboltypes or classes to use enumerations elegantly. No matter which method is used, you should pay attention to the naming and usage specifications of enumeration values, and avoid problems such as naming conflicts and repeated definitions.