How to get the object name in nodejs

Node.js is a very popular back-end programming language that can be used to write web applications, web servers, command line applications, and more. In Node.js, we often need to get some of its properties or methods by analyzing the passed in object, so getting the object name is also very important. Next, this article will introduce several methods on how to get the object name.

1. Use the typeof keyword

In JavaScript, you can use the typeof keyword to get the type of a variable, and objects are no exception. We can use the typeof operator to determine whether an object is an object type. If so, we can use its toString method to get the name of the object.

var obj = {name:'Node.js'};
console.log(typeof obj);    // 输出 "object"
console.log(obj.toString());    // 输出 "[object Object]"

As can be seen from the above code, use the typeof operator to determine that the type of obj is object. The class name to which obj belongs is Object, so its output result is "[object Object]".

In addition to directly using the typeof keyword to determine the object type, we can also encapsulate the process of obtaining the object name by wrapping a layer of functions to make the code more readable and concise.

function getObjectName(obj) {
    return Object.prototype.toString.call(obj).slice(8, -1);
}

var obj = {name:'Node.js'};
console.log(getObjectName(obj));    //输出 "Object"

The getObjectName function above encapsulates the process of obtaining the object name. We pass an object obj to it. It first obtains the class name to which obj belongs through Object.prototype.toString.call(obj), and then through slice The method gets the substring of the class name string, that is, we get the object name we want.

2. Use the constructor attribute

In JavaScript, each function has a constructor attribute, through which the constructor of the function can be obtained, so we can use the constructor attribute of the object to Get the name of this object. The following is an example:

function Person(name, age) {
    this.name = name;
    this.age = age;
}

var p = new Person('Tom', 18);
console.log(p.constructor.name);    // 输出 "Person"

In the above code, we define a Person function, and then create an object p through the new keyword, and then we can obtain the object through p.constructor.name Constructor name, which is "Person".

It is very simple to use the constructor attribute to get the object name, but it should be noted that this method only applies to objects created through the constructor, and is not valid for general objects.

3. Use the Object.keys() method

The Object.keys() method can get the name of an object's own properties. If we already know the property name of an object, then through The attribute name can be used to obtain the value of the object's attribute, thereby obtaining the object name. For example:

var obj = {
    name: "Tom",
    age: 18
};

var propName = Object.keys(obj)[0];
console.log(propName);    // 输出 "name"
console.log(obj[propName]);    // 输出 "Tom"

In the above code, we first use the Object.keys() method to get the attribute name array of the obj object, and then we use the array subscript to get the name of the first attribute (i.e. " name"), and then use obj["name"] to get the value of the attribute (ie "Tom").

It should be noted that this method is only applicable when the object has only one attribute. If the object has multiple attributes, the object name cannot be obtained accurately.

4. Use the Object.prototype.toString() method

The Object.prototype.toString() method can return the string representation of an object. The specific method and typeof operator obtain the object name. In a similar way, we can also use it to get the name of an object.

var obj = {name: "Node.js"};
console.log(Object.prototype.toString.call(obj));    // 输出 "[object Object]"

In the above code, we obtain the string representation of the object through Object.prototype.toString.call(obj), and then we can parse the name of the object from the string.

It should be noted that this method is also only applicable when the object has only one attribute.

5. Summary

In Node.js programming, we often need to get the name of the object. This article introduces four commonly used methods to get the name of the object. They are:

• Use the typeof keyword
• Use the constructor attribute
• Use the Object.keys() method
• Use the Object.prototype.toString() method

It is necessary to choose the appropriate method according to the specific situation to achieve the best use effect. Hope this article is helpful to you.

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