Mobile Development - Lecture 8

 

 Mobile Development- Using React Native - Lecture 8

Lecture Outcome:

At the end of the lecture, students will be able to know about

• COLLECTIONS AND INTRO TO OOP (FOR REACT USERS)

• run COLLECTION.js using VS Terminal (Practical)

# COLLECTIONS AND INTRO TO OOP (FOR REACT USERS)

# COLLECTIONS
    -> SET ({1,3,4,2} {'a','b','c'} {"asf","saf","saf"})
        -> [1,2,3,4,5], [1,3,4,3,2,1] ✅
        -> [1,2,"name",3, true] ❌
            SET ===  ARRAY 
<!-- IN AN ARRAY DATA TYPE OF ELEMENTS SHOULD BE SAME -->
    -> FreeHand
        -> OBJECT
            {'a',1,[1,3,4], "ahsfha", true }
<!-- FREE HAND IS AGNOSTIC FROM DATATYPE SIMILARITY -->

<!-- KEY PAIR SOLUTION -->

        KEY : VALUE
      {
          x : 33,
          y : "erozgar",
          z : false
      }

<!-- to create an OBJECT we have to use KEY PAIR structure -->


## ACCESS OF A VALUE OUT OF COLLECTIONS
     
     myArray  =  [1,44,3,4,5]
              
    const firstValue = myArray[1] ==> 44

# INDEXING ==> 0  = 1
<!-- COMPUTER STARTS COUNTING FROM 0 -->
<!-- trying to access an index which is not there is known as ArrayIndexOutOfBoundException -->

COLLECTION.js

const arrayOne = [1,2,3,4,5]


const objectOne = {
    1: "value",
    2: 33,
    3: [1,3,4],
    4: true,
    5: 'a'
}

// console.log(objectOne);


/// lets access the value in an ARRAY

const myArray = [33,22,11,44,55]
const firstValue = myArray[5]
console.log("firstValue", firstValue);