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Similarities and differences between Object.defineProperty and Object.defineProperties of js

 The Object.defineProperty() method defines a new property directly on an object, or modifies an existing property of an object, and returns the object. Contains three parameters: the object to be manipulated, the specified attribute of the manipulated object, and the attribute descriptor to be defined or modified. The last parameter is an object. You can specify its value, enumerable: control whether the property can be enumerated, the default value is false. writable: Controls whether the property can be modified, the default value is false. configurable: Controls whether the property can be deleted, and whether other properties except the value and writable properties can be modified. The default value is false.get: Called when the value of this property is obtained. set: Called when the value of this property is overridden.

Core points:

  • The configurable attribute indicates whether an object's properties can be deleted, and whether other attributes other than the value and writable attributes can be modified. When it is set to false for the first time, it is not possible to rewrite it. The attribute value also cannot be deleted and modified.
  • The configurable attribute indicates whether an object's properties can be deleted, and whether other attributes other than the value and writable attributes can be modified. When it is set to false for the first time, it is not possible to rewrite it. The attribute value also cannot be deleted and modified.

        var obj = {};
        Object.defineProperty(obj,"hobby",{
            value:"swim",
            enumerable:true,
            writable:false,
            configurable:false
        })
        Object.defineProperty(obj,"hobby",{
            value:"sing",
            // configurable:true,//err
            writable:false
        })
        console.log(obj.hobby)

The following are the default values in the two defined cases, pay special attention to

var oobj = {};
 //One
 obj.hobby = "swim";
 // The default values are as follows:：
 Object.defineProperty(obj, "hobby", {
   value: swim,
   writable: true,
   configurable: true,
   enumerable: true
 });
 
 
 // Two
 Object.defineProperty(obj, "hobby", { value : "sing" });
 // The default values are as follows:
 Object.defineProperty(obj, "hobby", {
   value: "sing",
   writable: false,
   configurable: false,
   enumerable: false
 })

To read the property value of the property, use Object.getOwnPropertyDescriptor

        var obj = {};
        Object.defineProperty(obj,"hobby",{
            value:"swim",
            enumerable:true,
            writable:false,
            configurable:false
        })
        console.log(Object.getOwnPropertyDescriptor(obj, "hobby"))

When we want to set multiple properties for an object, we need to use the Object.defineProperties() method. The specific usage is similar.

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