Javascript Object basics

What is an object in JavaScript?

Any thing that is not a js primitive is an object. An object is a collection of keys with there own values or key value pairs. Each value can be of any type.

• An object is stored in the heap memory. All javascript objects maintain a reference to it, as opposed to a full copy of it. When checking for object equality, it checks the reference - not the actual value of properties making objects mutable.

How do you create and object?

Here are three ways we create an object in javaScript are:

1. Object literal
   

   // we are literaly typing out our object. 
   const objectOne = {};
                     👆🏽
   

2. new Object();
   

   // use the js new key word to create a new object.
   const objectTwo = new Object();
                         👆🏽
   

3. Object.create({ })
   

   // creates a new object from an existing object.
   const objectTwo = Object.create({ });
                               👆🏽
   

   Properties

   • Property is another term used for key value pairs that are stored in an object.
   • Names of properties are unique values that can be coerced to a string not including words like function, var, return. The name or key points to a value.
   • Property values can be of any type. Including functions witch we call methods.

   Manipulating Properties

   Setting properties can be done at two stages.

   • During the creation of our object.
   • After the creation of our object.

   Adding properties during its creation

   • as of ES6 (ECMAScript 6) we can also use a new short hand for setting properties whos value and name are the same.

   // in the creation on this object we are declaring its properties.
    const anime = { 
       title: 'naruto',
       discription: 'an anime about a ninja who is just trying to be hokage',
     isLigit, 'isLigit'
       }
   
       const anime = {
       title: 'naruto',
       discription: 'an anime about a ninja who is just trying to be hokage',
     isLigit // ES6 no need to state the value if it is the same as the key
       }
   

   Two ways of adding properties after its creation

   • Dot notation & Bracket notation
     Dot notation can only access names or keys that do not stat with a digit or does not include spaces
     

     // this works
     anime.rating = '100/10';
     // this does not 
     anime.my name = 'Jay';
     

     Bracket notation has no problem accessing names or keys that starts with a digit or contains spaces.
     

     anime[20] = '100/10'
     anime['my name'] = 'Jay';
     

     Getting properties

     We can properties in the same way we set them.
     

     const anime = anime.title;
     console.log(anime) // logs 'naruto'
     
     const anime = anime['title'];
     console.log(anime) // logs 'naruto'
     

     Deleting properties.

     Object Properties can be deleted using the delete keyword.
     

     delete anime.title;