Getting to know Reflect

Reflect

Reflect is a built-in object that provides methods to intercept JavaScript operations. These methods are the same as those of proxy handlers . Reflectis not a function object, so it is not constructible.

Unlike most global objects Reflect, it is not a constructor, so it cannot be called via the new operator , or the Reflectobject as a function. ReflectAll properties and methods of are static (like Mathobjects).

ReflectThe object provides the following static methods, named the same as the proxy handler methods (en-US) .

Some of these methods are the Objectsame as , although there are some subtle differences between the two

static method

• Reflect.apply(target, thisArgument, argumentsList)

  To call a function, you can pass an array as a call parameter. Function.prototype.apply()Similar to function .

• Reflect.construct(target, argumentsList[, newTarget\])

  new Operating on the constructor is equivalent to executing new target(...args).

• Reflect.defineProperty(target, propertyKey, attributes)

  and Object.defineProperty()similar . If the setting is successful, it will returntrue

• Reflect.deleteProperty(target, propertyKey)

  As a function deleteoperator, it is equivalent to execute delete target[name].

• Reflect.get(target, propertyKey[, receiver\])

  Get the value of a property on an object, similar totarget[name]。

• Reflect.getOwnPropertyDescriptor(target, propertyKey)

  Similar to Object.getOwnPropertyDescriptor(). If the property exists in the object, return the corresponding property descriptor, otherwise return it undefined.

• Reflect.getPrototypeOf(target)

  Similar to Object.getPrototypeOf().

• Reflect.has(target, propertyKey)

  Determining whether an object has an inattribute has exactly the same function as the operator.

• Reflect.isExtensible(target)

  Similar to Object.isExtensible().

• Reflect.ownKeys(target)

  Returns an array containing all own properties (excluding inherited properties). (similar to Object.keys(), but not affected by enumerable影响).

• Reflect.preventExtensions(target)

  Similar to Object.preventExtensions(). return one Boolean.

• Reflect.set(target, propertyKey, value[ receiver])

  A function to assign a value to a property. Returns one Boolean, or if the update was successful true.

• Reflect.setPrototypeOf(target, prototype)

  A function to set the prototype of the object. Returns one Boolean, or if the update was successfultrue。

example

Check if an object has a specific property

const apiJson = {
    
    
  name: 'static data',
  type: 'static',
  getData: function() {
    
    
    console.log(`获取的数据类型为：${
      
      this.name}`);
  }
}

Reflect.has(apiJson, 'type');  // true
Reflect.has(apiJson, 'age');   // false

Add a new property to this object:

Reflect.set(apiJson, 'data', '静态数据1');

Return the properties of this object itself:

Reflect.ownKeys(apiJson)

// 检测一个对象是否存在特定属性
  const apiJson = {
    
    
    name: 'static data',
    type: 'static',
    getData: function() {
    
    
      console.log(`获取的数据类型为：${
      
      this.name}`);
    }
  }

  console.log(Reflect.has(apiJson, 'type'));  // true
  console.log(Reflect.has(apiJson, 'age'));   // false

  // Reflect.set(apiJson, 'data', '静态数据1');
  console.log(Reflect.set(apiJson, 'data', '静态数据1')); // true

  // 返回这个对象自身的属性
  console.log(Reflect.ownKeys(apiJson));

For detailed documentation, please check MDN: https://developer.mozilla.org/zh-CN/docs/Web/JavaScript/Reference/Global_Objects/Reflect