arrowFunctionBasics.html

<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="utf-8">
        <title>Arrow Function Basics</title>
    </head>
    <body>
        <p href="https://javascript.info/arrow-functions-basics">Arrow Function Basics</p>

        <p href="https://javascript.info/arrow-functions">Follow up page</p>

        <script>

            /*

            // simple concise syntax for creating functions, often better
            // than FEs.

            let func = (arg1, arg2, ...a, argN) => expression;

            // a shorthand way of writing

            let func = function(arg1, arg2, ...a, argN) {
                return expression;
            };

            */

            /*

            // Full example

            let sum = (a, b) => a + b;

            // shorthand for
            

            let sum = function(a, b) {
                return a + b;
            };

            
            alert(sum (1, 2) ); // 3

            */

            // parenthesis can be omitted if a single argument
            // let double = n => n*2; == let double = function(n) { return n*2 };
            // If NO argument, parentheses will be empty but should still be in place
            // let sayHi = () => alert('hello!');

            // arrows can dynamically create functions as well

            /*

            let age = prompt('How old are you?', 18);

            let welcome = (age < 18) ?
              () => alert('Hello!') :
              () => alert('Greetings!');

            welcome();

            */

            // without curly braces (...args) => expression
            // right side is expression, function evals and returns result

            // With curly braces (...args) => {body}
            // brackets allow multiples statements inside the function
            // !! an explicit 'return' is required to return something.

            // Tasks

            //oof.

            /*

            let question = ('do you concur?');

            let ask = (question);
            
              
            let welcome = (ask, yes, no);
              () => confirm(question) (yes(), alert('You agreed'));
              () => no() (alert("you cannceled."));

              */

              // Solution
              // the answer was in the question replace FUNCTION EXPRESSIONS with arrow func

              function ask(question, yes, no) {
                  if (confirm(question)) yes();
                  else no()
              }

              ask (
                  'Do you concur?',
                  () => alert('you agreed'),
                  () => alert('you don\'t agree?')
              )
            
            
        </script>
    </body>
</html>