Func.js

//Function Declaration / defining 
//Block of code that performs a specific task , can be invked whenever needed.Function saves from redundancy means repeating 
// Function Definition & Function Call or Invoke
function myFunction(msg) {
    console.log(msg);
}
myFunction("I love TS"); // arguments
// Function to Calculate Sum & return
// Imp is that function parameters -> like local variable -> Block scope of function
function sumFunction(a, b) {
    let s = a + b;
    return s; // returns are last to right else what ever written after will definetly not run
}
let val = sumFunction(3, 4);
console.log(val);
// OPTIONAL PARAMETERS in Functions / parameterized function
function disp_details(id, name, mail_id) {
    console.log("ID:", id);
    console.log("Name", name);
    if (mail_id != undefined) // The function prints the value of mail_id only if the argument is passed a value.
        console.log("Email Id", mail_id); //If an optional parameter is not passed a value during the function call, the parameter’s value is set to undefined
}
disp_details(123, "John");
disp_details(111, "mary", "mary@xyz.com");
//ARROW FUNCTION. Compact way of writing a Function , Arrow function stores its value in a variable.
// () => {} Syntax for Arrow Function
let arrowFunction = (x, y) => {
    let sum = x + y;
    return sum;
};
let vals = arrowFunction(8, 10);
console.log(vals);
//Arrow -2
let prepNewMeal = (dishName) => {
    console.log("Making:" + dishName);
};
prepNewMeal("Russian Salad");
//Calculate an Averge bt 3 numbers with Arrow Function
let AvgFunction = (a, b, c) => {
    let avg = (a + b + c) / 3;
    return avg;
};
let result = AvgFunction(40, 20, 22);
console.log(result);
//Q: Function that takes a String as an argument and returns the number of Vowels in the string
function countVowels(word) {
    word = word.toLowerCase();
    let count = 0;
    for (let chr of word) {
        if (chr === "a" ||
            chr === "e" ||
            chr === "i" ||
            chr === "o" ||
            chr === "u") {
            count++;
        }
    }
    return count;
}
const inputWord = "Apna College";
const vowelCount = countVowels(inputWord);
console.log(`Number of vowels in "${inputWord}": ${vowelCount}`);
// Create an arrow funtion to perform same task
let countvowels = (word) => {
    word = word.toLowerCase();
    let count = 0;
    for (let chr of word) {
        if (chr === "a" ||
            chr === "e" ||
            chr === "i" ||
            chr === "o" ||
            chr === "u") {
            count++;
        }
    }
    return count;
};
const inputWords = "Apna College";
const vowelsCount = countVowels(inputWord);
console.log(`Number of vowels in "${inputWord}": ${vowelCount}`);


// Callback Function: In TS a function can be passed as an arguemnts to another funtion 
// for an array (only used for Arrays) forEach method is used by using call back funtion
// Interview Question: forEach is also called as Higher order function/ Method having parameters/n
// and return other function as output, where there is a call back function as paramter in another function it becomes a higher order function.

let arr = ["Islamabad", "lahore", "Karachi"];
arr.forEach((val, idx, arr) => {
    console.log(val.toUpperCase(), idx, arr);
});

//Practice Question : for a given array , print squre of each value using forEach loop.
let arryNum = [1, 2, 3, 4, 5, 6];
arryNum.forEach((val) => {
    console.log(val * val);
});
export {};
// Or another way 
// let calSqure =(val) =>  {
//   console.log(val * val)
//  }
//  arryNum.forEach(calSqure);
// function calculateAverage (num1: number, num2: number) { // this method name is Calculate averge and we have passed two parranmeters num1 and num2, or this method is beng defined with two Parameters
//     return (num1+num2)/2; // when this method return value its type will be number
// }
// let avg = calculateAverage(20,50); //20 +50/2 =35
// console.log(avg);
//same method with arrow Function
// // let avg2 = (num1: number, num2: number) => (num1+num2)/2; 
// let avg2 =(num1: number, num2: number) => {
// let myAvg = (num1+num2)/2;
// return myAvg;
// }
// // a Function which do not return a value 
// function calculateAverage2() {
//     console.log("Calculating Average");   
// }
// // using thsi function in a variable to store a value
// let avg3 = calculateAverage2();
// console.log(avg3)
// let f3 = (age:number,name:String) => {
// return `Mr .${name}, your age is ${age}`;
// }
// console.log(f3 (100,"Aimon")); 
// //Optional Parameters
// function optParmas(param1?:number, param2:string = "Gamma",param3:number=10){  // Optional parameter should be at aend, if all 3 parameters are optional itr will work
//     console.log(`${param1}, ${param2}, ${param3}`);
//     return `${param1}, ${param2}, ${param3}`;
// }
// let xyz = optParmas(10,"Alpha",20); // if we set some varibale default at the end as above 
// console.log(xyz);
// let xyz2 = optParmas(10,"Beta") //  if we call it this way what should print here
// console.log(xyz2); // what would print here, printing two times as once in method and once we ourself printing
// let xyz3 = optParmas(10); // where there is a no value and make that print it is rule of thum that underfined print there and first parameter can never be optional
// console.log(xyz3);
// // why first parameter can not be optional below
// // before required paramter there could not be a optional paramter this is rule of thum
// function optParams2(num1?:number , num2?:number) {
// console.log(num1);
// console.log(num2);
// }
// //optParams2();
// //optParams2(10);
// optParams2(10,20);
// //Functions - and syntax:
// // function fun_name(parameter) {
// //code
// // }
// //function declaration
// function greet(name: string) {
//     console.log("Hello, " + name.toUpperCase() + "!!");
//   }
//   greet("John"); //function call
//   //function declaration
//   function Welcome(parameter: string) {
//     console.log(`Welcome ${parameter}`);
//   }
//   Welcome("wania"); //function call
//   Welcome("Class 54");
//   function getFavoriteNumber(): string {
//     return "Value is positive";
//   }
//   // console.log(getFavoriteNumber())
//   getFavoriteNumber();
//   //Arrow Function
//   let sum1 = (x: number, y: number): number => {
//     return x + y;
//   };
//   // console.log(sum1(2,3))
//   //Arrays
//   let arr = [1, 2, 3, 4, 5, 6];
//   console.log(arr[0]);