Scope-Safe Constructors

constructor.js

/**
 * Code example from <professional javascript for web developers v3 p733>
 */
// problem
function Person(name, age, job){
  this.name = name;
  this.age = age;
  this.job = job;
}

var person = Person(“Nicholas”, 29, “Software Engineer”);
alert(window.name); //”Nicholas”
alert(window.age); //29
alert(window.job); //”Software Engineer”

// solution
function Person(name, age, job){
  if (this instanceof Person){
    this.name = name;
    this.age = age;
    this.job = job;
  } else {
    return new Person(name, age, job);  
  }
}