Java-script-course/07-functions.html at main · Dev-Soft-tech/Java-script-course · GitHub

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<!DOCTYPE html>
<html>
  <head>
    <title>Functions</title>
  </head>
  <body>
    <script>
      // function function1() {
      //   console.log('hello');
      //   console.log(2 + 2);
      // }
      // function1();
      // function1();
      // /*
      // RULES for functions naming
      // 1. Can not name a function function.
      // 2. can not start with a number.
      // 3. can not have a space in the name.
      // 4. can noyt use special characters like @, #, $, %, ^, &, *, (,
      //   ), !, +, =, {, }, {,} and so on
      // 5. can not use reserved keywords like ffunction,
      // var, let, const, if, else, for, while, do, switch, case, break, continue, return, try, catch, finally, throw, class, extends, super, import, export and so on.
      //   */

      function calculateTax(parameter1) {
        console.log (parameter1 * 0.1);
      }
      // the parame ter only exist inside the function.
      //the value 2000 and 5000 are called arguments.
      //parameter1 is a parameter name.
      //is follows the same naming rules as a variable name.
      //a parameter helps put a value into a function.
      // parameter is a placeholder for a value that will be passed when a function is called.
      calculateTax(2000);
      calculateTax(5000);

      //multiple parameters
      function multiparameter(a, b, c, d) {
        console.log(a + b + c + d);
      }
      multiparameter(1, 2, 3, 4); //100

      //set a default value for a function parameter.
      function multiparameter(a, b, c, d = 0) {
        console.log(a + b + c + d);
      } //from the code the default value is 0.
    </script>
  </body>
</html>