jess_lesson.yaml

title: Sample Lesson
author: Ferran Maylinch

# Minimum app version needed for this lesson
minAppVersion: "1.0"

exercises:

  - title: Sample Exercise

    # `intro` is displayed when the exercise is started.
    # It's a list of `text` (with some basic Markdown), `image` and `code` sections.
    intro:
      - text: "**Jess** is an app that helps you learn programming by using [JavaScript](https://www.javascript.com)."
      - image: http://i.imgur.com/WEA5N6k.png
      - text: As a sample exercise, you will print your name using the **`log`** function.
      - code: |
          // Example
          log("Jess");
      - text: >
          Your task is simple: in the editor below, just **write your name between the quotes**,
          and then run the code using the `RUN` button.

    # `code` is optional (it's the initial code in the editor)
    code: |
      // Write your name inside the quotes
      log("");

    # `check` is optional but you will usually want to check whether the user completed the task.
    #   It's a js function that receives an object containing `logs` (array) and `tries` (number).
    #   If the user doesn't pass the task return: { ok:false, message:"some message or hint" }
    #   If the user passes the task return: { ok:true, ... }. Any properties you add can be used in explanation.
    check: |
      function(jess) {
        if (jess.logs.length >= 1 && jess.logs[0]) {
          return { ok:true, name:jess.logs[0] };
        } else if (jess.logs.length > 1) {
          return { ok:false, message:"Use the `log` function just once" };
        } else if (jess.logs.length === 0 || jess.logs[0].length == 0) {
          return { ok:false, message:"Write something inside the quotes." };
        }
      }

    # `explanation` is displayed after the task is successfully completed (structured like `intro`)
    # You can use properties added to the result object you return in `check`.
    explanation:
      - text: Well done **{{name}}**! After you complete an exercise, you will see some explanation about what you learnt.
      - text: In this case, you have printed your name in the console (the brown view) using the `log` function.
      - text: That was awesome, right? And many more exciting exercises are awaiting!


  - title: Current year?

    intro:
      - text: Print the current year

    code: log("");

    check: |
      function(jess) {
        if (jess.logs.length >= 1 && jess.logs[0] == new Date().getFullYear()) {
          return { ok:true };
        } else {
          return { ok:false, message:"Nope! You tried " + jess.tries + " times." };
        }
      }

    explanation:
      - text: You're a clever person!


  - title: Declare a variable

    intro:
      - text: Declare a variable named `age` and assign your age to it.

    check: |
      function(jess) {
        if ( typeof(age) === 'undefined' ) {
          return { ok:false, message:"You didn't declare the variable `age` or assigned anything to it." };
        } else if ( typeof(age) !== 'number' ) {
          return { ok:false, message:"You didn't asign a number to the variable `age`." };
        } else if ( age < 1 || age > 130 ) {
          return { ok:false, message:"Assign a reasonable number..." };
        } else {
          return { ok:true, age:age.toString() }; // It's better to always pass strings
        }
      }

    explanation:
      - text: You're {{age}} years old?? Really??