The new Operator#

In JavaScript, new is a syntactic sugar that simplifies the code writing and allows for the batch creation of object instances.
Syntactic sugar refers to a certain syntax added to a computer language, which does not affect the language's functionality, but makes it more convenient for programmers to use. Generally, the use of syntactic sugar can increase the readability of the program and thus reduce the chance of coding errors.

Example#

Suppose we don't use new to initialize and create 10 student object instances.

var stuGroup = [];
for(let i=0;i<10;++i){
    var obj = {
        name: i,
        hp: 100,
        mp: 1000,
        power: 100,
        defense: 100
    }
    stuGroup.push(obj);
}
console.log(stuGroup);

At this point, we will obtain 10 initialized student object instances. However, using the new keyword can simplify the operation, and we can also use the prototype chain to share properties and other operations.

function Student(i){
    this.name = i;
    this.hp = 100;
    this.mp = 1000;
    this.power = 100,
    this.defense = 100;
}
Student.prototype.from = "sdust";
var stuGroup = [];
for(let i=0;i<10;++i){
    stuGroup.push(new Student(i));
}
console.log(stuGroup);

Operation of the new Operator#

1. Create a new simple JavaScript object, i.e., {}.
2. Link this object (i.e., set this object's constructor) to another object.
3. Set the newly created object from step 1 as the context this.
4. If the function does not return an object, return the object created in step 1.

function _new(base,...args){
    var obj = {};
    obj.__proto__ = base.prototype;
    base.apply(obj, args);
    return obj;
}
function Student(i){
    this.name = i;
    this.hp = 100;
    this.mp = 1000;
    this.power = 100,
    this.defense = 100;
}
Student.prototype.from = "sdust";
var stuGroup = [];
for(let i=0;i<10;++i){
    stuGroup.push(_new(Student,i));
}
console.log(stuGroup);

Daily Question#

References#