JavaScript Learning Notes:

for...of

  • Example:
    • 
                    const arr = [1, 2, 3, 4, 5]

                    for (const num of arr) {
                        console.log(num);
                    }

    The for...of loop is ideal for iterating over iterable objects like arrays, strings, and Maps.

    Console Output:
    1
    2
    3
    4
    5


  • String Example:
    • 
                    const greetings = "Hello world!"
                    for (const greet of greetings) {
                        console.log(`Each char is ${greet}`)
                    }

    Console Output:
    Each char is H Each char is e Each char is l Each char is l Each char is o Each char is Each char is w Each char is o Each char is r Each char is l Each char is d Each char is !


    Map

  • Definition:

    • A Map is a collection of key-value pairs where both keys and values can be any data type.

    
                    const map = new Map()
                    map.set('IN', "India")
                    map.set('USA', "United States of America")
                    map.set('Fr', "France")
                    map.set('IN', "India")
                    console.log(map);

                    //Iterating KEY and VALUES at once
                    for (const [key, value] of map) {
                        console.log(key, ':-', value);
                    }
  • map.set()method adds new key-value pairs to the map.

    • Console Output: 

        
                         Map(3) {
                        'IN' => 'India',
                        'USA' => 'United States of America',
                        'Fr' => 'France'
                      }
                      
                      IN :- India
                      USA :- United States of America
                      Fr :- France