{"id":5866,"date":"2022-06-29T04:32:15","date_gmt":"2022-06-29T04:32:15","guid":{"rendered":"https:\/\/studysection.com\/blog\/?p=5866"},"modified":"2022-06-29T04:32:15","modified_gmt":"2022-06-29T04:32:15","slug":"constructor-design-pattern","status":"publish","type":"post","link":"https:\/\/studysection.com\/blog\/constructor-design-pattern\/","title":{"rendered":"Constructor design pattern"},"content":{"rendered":"

In Object-oriented programming, a constructor is a method used to initialize a newly created object after memory has been allocated for that object. In javascript, almost everything is an object. Object constructor is one of the most important topics that we may be interested in. <\/p>\n

To create specific types of objects object constructor is used. Preparing the object for use and accepting arguments a constructor can be used to set the values of properties and methods when the object is created. <\/p>\n

\"desgin\"\/<\/p>\n

Object Creation<\/h2>\n

There are multiple ways to create javascript objects.
\nVar obj = {};
\nVar obj = new Object();<\/code><\/p>\n

The Object constructor creates an object wrapper for a particular value. If no value is passed it will create an empty object.
\nThere are four ways to pass keys and values to an object.
\nobj.name = \u2018Sunil Sethi\u2019;
\nvar key = obj.name;<\/p>\n

Obj[\u2018name\u2019] = \u2018Sunil Sethi\u2019;
\nVar key = obj[\u2018name\u2019];<\/p>\n

Object.defineProperty(obj, \u201cname\u201d, {
\n\tValue : \u201csunil sethi\u201d,
\n\tWritable:true,
\n\tEnumerable : true,
\n\tConfigurable: true,
\n});<\/p>\n

Object.defineProperties(obj,{
\n \"name\":\"sunil\",
\n writable:true,
\n \"age\":30,
\n writable:false,
\n });<\/code><\/p>\n

Basic Constructor:<\/h3>\n

As Javascript doesn’t support the concept of classes, it supports the constructor function that works with objects. We can just prefix a call to a constructor function with the new <\/em><\/strong>keyword. We can make the function behave like a constructor and instantiate a new object with the members defined by that function. Under the constructor, the keyword this references the new object that is being created. The basic look of the constructor is as follows. <\/p>\n

function Display(name, age, roll){
\n this.name = name;
\n this.age= age;
\n this.roll = roll;
\n this.toString = function (){
\n return this.name + this.age + this.roll;
\n }
\n}
\nvar display = new Display(\"sunil\",32,101);
\nconsole.log(display.toString());<\/code><\/p>\n

The above is the simplest version of the constructor pattern, but it has some problems. <\/p>\n