facg6-basic-js-workshop

• Values & Types

      //difference between 
      24;
      // and 
      "24";
  
      // explicit change of type (conversion)
      String(24);
      Number("24");
      // implicit change of type (coercion)
      24 + "";

• Variables

      //why this works?
      a = 24;
      var a;
  
      // though we prefer it like this
      // always declare variables before using them for less confusing code
      var a;
      a = 24;
      //or
      var a = 24;

• Truthy & Falsy values

      // what are falsy values
      0 -0 NaN
      ""
      false
      null
      undefined

      var a = 7;
      if (a) {
        console.log(a);
      }
  
      if (b) {
        console.log(b);
      }

      let defaultName;
      // instead of:
      if (username) {
      defaultName = username;
      } else {
      defaultName = 'Stranger';
      }
      // we can just do this
      defaultName = username || 'Stranger';

• Difference between if-else & switch

      // if-else are better for boolean values
      if (inputValue) {
        // do some action
      } else {
        // return empty value error
      }
  
      // switch are better for Multi way branching
      switch (tabValue) {
        case "welcome":
          // show welcome section
          break;
        case "main":
          // show main section
          break;
        case "about-us":
          // show about us section
          break;
        default:
          // show home section
      }

• Loops

      // infinite loops
      // how to break the loop
  
      for (a = 0; a < 10; a = a + 1) {
        console.log(a);
      }
  
      // same thing we can do with while
      let a = 0;
      while (true) {
        console.log(a);
        a++;
        if (a >= 10) {
          break;
        }
      }

• Functions & scopes

      // why we need function
      // ways to declare a function
      function foo () {}
      var foo = function () {}
      var foo = () => {}   // arrow function ES6
      
      // difference between declaring and calling
      // function returns a value
      // parameters vs arguments
      // scopes
      function foo (b) {
        var c = 7;
        a = a + 8;  //can access a from parent scope "global"
        return a/c;
      }
      var a = 5;
      console.log(b, c); // Reference Error

• Challenge1: inspired from YDNJS

  • Write a program to calculate the total price of your phone purchase. You will keep purchasing phones (hint: loop!) until you run out of money in your bank account.
  • After you've calculated your purchase amount, add in the tax, then print out the calculated purchase amount, properly formatted.
  • Finally, check the amount against your bank account balance to see if you can afford it or not.

  ---

  • You should set up some constants for the "tax rate," "phone price," as well as a variable for your "bank account balance.""
  • You should define a function for calculating the tax and a function for formatting the price with a "$" and rounding to two decimal places.