What are the characteristics of javascript object properties
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Object characteristics:
1. Writable: writable
Writable indicates whether the value of the property can be set
Let obj = {age:10} obj.age = 1 / / reassign the attribute console.log (obj.age) / / 12, enumerable: enumerable
The enumerable attribute refers to whether the property name can be returned in the for/in loop. By default, both own and inherited properties can be enumerated.
Let obj = {name: "zhang", age:20, sex: "male"} let newObj = Object.create (obj) newObj.height = 200for (p in newObj) {console.log (p, "- >", newObj [p])}
Output:
Height-> 200
Name-> zhang
Age-> 20
Sex-> male
3. Configurable: configurable
Configurable indicates whether attributes can be deleted through delete
Let obj = {name: "jim"} delete obj.name / / the attribute will not exist console.log (obj.name) / / undefined after deletion
The above three properties in the object are all true by default. If you want to change the default values for these features, you can use the Object.defineProperty () method. DefineProperty receives three parameters, the object, the attribute name to be modified, and the eigenvalue object.
For example, if you want to set the writable of the sex property to false, you can use the defineProperty () method to do so
Let obj = {name: "zhang", age:20, sex: "male"} Object.defineProperty (obj, "sex", {writable:false}) obj.sex = "female" console.log (obj.sex) / / male
When writable is set to false, even if the sex property is re-assigned to female, its value is still the original male, and the enumerable and configurable properties of the property can be configured through similar operations.
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