1. What does the new operator do

The new operator creates an instance of a user-defined object type or of a built-in object with a constructor. The new keyword does the following: creates an empty simple JavaScript object (that is {}); Link this object (that is, set its constructor) to another object; Use the new object created in Step 1 as the context for this; If the function does not return an object, this is returned.

2. Simple implementation

function create(Con, ... args){
  // Create an empty object
  let  obj = Object.create(null);
  // Point the empty object to the constructor's prototype chain
  Object.setPrototypeOf(obj, Con.prototype);
  // obj binds to the constructor to access properties in the constructor, obj.con (args)
  let result = Con.apply(obj, args);
  Return if result is an object
  // The new method is invalid, otherwise obj is returned
  return result instanceof Object ? result : obj;
}

/ / test
function company(name, address) {
    this.name = name;
    this.address = address;
  }

var company1 = create(company, 'yideng'.'beijing');
console.log('company1: ', company1);
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