JavaScript Data structures part I, JavaScript Objects.
1.JavaScript Object.
An Object is a collection to properties, and a property is an association between a name (or key) and a value, every property has a unique key string that is unique within that object.Creating objects
There are a lot of ways of creating JavaScript objects here i am going to discuss only three of them.
- Using object constructor
var newObject = new Object();
- Using Object prototype's create method
var newObject = Object.create(null)//this will create an empty object since we passed null in it
- Using bracket syntax sugar{}
var newObject = {}//this also will create an empty object as well.
There are two ways of getting property values from objects;,one is through dot notation and the other is through square brackets. For example consider the following object.
var student = {
"name":"justine",
"age":32
}
a)Using dot notation.
console.log(student.name)//justine
b)Using the square brackets
console.log(student['age'])
Square brackets are much more useful when the key name is a string with some other characters that makes it not qualified as a JavaScript literal name for example a space
ie. console.log(student.second name)//this will print an error
but
console.log(student['second name'])//this will not result to an error
II.Setting properties in objects
As it is to getting properties values from objects there are also two ways of getting values from objects
a)Using the dot notation
student.surename = "peterson"
This will create a property with surename as key and peterson as the value
console.log(student['surename']) //if we run this to console will print peterson
b)Using the square bracket notation
student['course'] = "computer engineering"
console.log(student.course)//print computer engineering
III.Deleting properties in objects
we can delete properties from objects by using the delete key word,for example;-
delete student.course;//this will delete the course property from the students
or
delete student['name']
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