This PR is the solution to the 'js basics' #Issue1

1-js-basics/solution.md

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+# 1-JS-Basics  
+
+---
+---
+
+## 1. Subtopic 1 - data-types
+---
+### Challenge  
+let age = 1; let Age = 2; age == Age (resolves false -- why?). What other gotchas can you find?
+---
+- Here the variable **age** stores 1 whereas **Age** stores 2.
+- So age==Age resolves false because the variables in JavaScript are case sensitive. It means 1==2 which is obviously false.
+- Some other **Gotchas** also occur because JavaScript is a not a Strictly types language. <br>
+1. `'0' == 0` returns true. Whereas `'0' === 0` return false. This is because o type coersion in Javascript.
+2. `'5' + 2` will give 52, `'5' - 3` will give 3, `'5' * 2` gives  10.
+3. There are values which are considered **falsy** like - `false`, `0`, `''`, `null`, `undefined`, `Nan`. `if (''){ console.log("Hello")}` wont run where as `if (' '){console.log("Hello")}` hello will run as there is a space.
+4. JavaScript returns the datatype of null as object which is misleading. `console.log(typeof(null))` returns object. Use === to check for null.
+
+---
+
+### Assignment 
+Imagine you are building a shopping cart. Write some documentation on the data types that you would need to complete your shopping experience. How did you arrive at your choices?
+---
+The Entities associated with a shopping cart would be **cart**, **user**, **product** and **Location**
+For each entity, the Datatypes would be,
+- Cart
+    - totalItems : `number`- displays total items in the cart.
+    - totalPrice : `number`- display total amount to be paidfor items in the cart.
+    - discount : `number`- the discount % given to the totalPrice.
+    - items : `Array of Objects`- This array contains objects of products.
+- User
+    - userid : `String`- unique id of a particular user.
+    - username : `String`- Name of Customer.
+    - emailid : `String`- contains email id of the customer.
+    - isLoggedIn : `boolean`- Checks if the user is logged in to their account.
+    - userAddress - `String`- shows the customer's address.
+- Product
+    - productid : `String`- unique id for each product.
+    - productName : `String`- Name of Product
+    - quantity : `number`- To display the quantity of each product.
+    - price : `number`- To display the price of each product.
+    - isAvailable : `boolean`- To display if the product is in stock.
+- Location 
+    - deliveryAddress : `String`- Address to which the item is to be delivered.
+    - expecteddate : `String`- Expected time and date of delivery for the location.
+
+---
+
+### Review and Self-Study
+Exercise Done : **Get URL and URL Parts in JavaScript**
+- I tried the exampole code in VSCode and verified it. 
+- Things I Learnt
+    - A url can be divided into parts and connected again in JavaScript using split() function. 
+    - The URL broke down into parts can be stored inside variables and the URL can be reconstructed with **+** operator. 
+    - A URL can also be stored in a array.
+    - The URL path can be manipulated and connected back again.
+
+---
+---
+
+## 2. Subtopic 2 - Functions-Methods
+---
+### Challenge
+Can you articulate in one sentence the difference between functions and methods? Give it a try!
+---
+Functions can take input arguments and return output values. On the other hand, a method is a function that is associated with an object in object-oriented programming. Methods are functions that are called on objects and can modify or access the object's properties.
+
+---
+
+### Assignment
+Create different functions, both functions that return something and functions that don't return anything.
+See if you can create a function that has a mix of parameters and parameters with default values.
+---
+1. Function that returns something
+    ```
+    function thisReturns(x, y){
+        z = x + y;
+        return z;
+    }
+    console.log(thisReturns(5, 10))
+    ```
+    This function returns 15.
+
+2. Function that doesn't return anything.
+    ```
+    function thisDoesNotReturn(x, y){
+        console.log(x+y)
+    }
+    thisDoesNotReturn(10, 10)
+    ```
+    This function doesn't return anything. It just prints 20.
+
+3. Function with mix of parameters and parameter with default values
+    ```
+    function mixed(x, y = 5){
+        console.log(x+y)
+    }
+    mixed(10)
+    ```
+    Here, 10 is assigned to the variable x and y has default value 15. So it prints 15.
+
+---
+
+### Review and Self Study
+Arrow functions cannot be used as methods. They are a better replacement to anonymous functions and traditional function expression. 
+1. Without arrow function
+    ```
+    const obj = {
+    num: 100,
+    }
+
+    const add = function (a, b, c) {
+    return this.num + a + b + c;
+    }
+    console.log(add.call(obj, 1, 2, 3));
+    ```
+2. With arrow function
+    ```
+    const obj = {
+    num: 100,
+    }
+    const add = (a, b, c) => this.num + a + b  + c;
+    console.log(add.call(obj, 1, 2, 3));
+    ```
+Both will return the output 106.
+
+---
+---
+
+## 3. Subtopic 3 - making-decisions
+---
+### Challenge
+Create a program that is written first with logical operators, and then rewrite it using a ternary expression. What's your preferred syntax?
+---
+- Using Logical Operators
+    ```
+    let x = 50, y = 10;
+    if (x > y){
+        greatest = x;
+    }
+    else{
+        greatest = y;
+    }
+    console.log(greatest);
+    ```
+
+- Using Ternary Expression
+    ```
+    let x = 50, y = 10;
+    const greatest = (x>y) ? x : y;
+    console.log(greatest);
+    ```
+There both give the same output 50.
+
+---
+
+### Assignment
+``` 
+let allStudents = ['A', 'B-', 1, 4, 5, 2];
+let studentsWhoPass = [];
+for (let i=0; i<allStudents.length; i++){
+    let student = allStudents[i];
+    if (typeof(student) === 'number' && student > 3){
+        studentsWhoPass.push(student);
+    }
+    else if(typeof(student) === 'string' && ['A', 'A-', 'B', 'B-', 'C'].includes(student)){
+        studentsWhoPass.push(student)
+    }
+}
+console.log("Students who Passed : "+studentsWhoPass)
+```
+
+---
+---
+
+## 4. Subtopic 4 - arrays-loops
+---
+### Challenge 
+There are other ways of looping over arrays other than for and while loops. There are forEach, for-of, and map. Rewrite your array loop using one of these techniques
+---
+- Using forEach
+    ```
+    let iceCreamFlavors = ["Chocolate", "Strawberry", "Vanilla", "Pistachio", "Rocky Road"];
+
+    iceCreamFlavors.forEach( (item) => {
+        console.log(item);
+    } )
+    ```
+    prints all values
+- Using for-of
+    ```
+    let Array = [1, 2, 3, 4, 5];
+
+    for (let item of Array){
+        console.log(item)
+    }
+    ```
+- Using map
+    ```
+    let Array = [1, 2, 3, 4, 5];
+
+    let newArray = Array.map((item) => item*10);
+    console.log(newArray);
+    ```
+    newArray contains all the values of Array multplied by 10.
+
+---
+
+### Assignment 
+Create a program that lists every 3rd number between 1-20 and prints it to the console.
+---
+- It is simple. Just give the iteration step as 3.
+    ```
+    for (let i=1; i<=20; i+=3){
+        console.log(i);
+    }
+    ```
+---
+