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Basics


Code Conventions​

Info:

  • Add a semicolon at the end of each executable statement

  • wrap line after an operators

    document.getElementById("demo").innerHTML =
    "Hello Dolly!";

Danger:

  • avoid code lines longer than 80 characters

  • Hyphens are not allowed in JavaScript. They are reserved for subtractions.


Syntax​

Info:

  • values
    • Fixed values are called Literals
    • Variable values are called Variables

Danger:

  • An equal sign = is used to assign values to variables.
  • Numbers are not allowed as the first character in names.

Placement​

Info:

  • You can place any number of scripts in an HTML document.
  • can be placed in the <body>, or in the <head> section
    • Placing at bottom <body> element improves the display speed, because script interpretation slows down the display.

  • inline

    <!DOCTYPE html>
    <html>
      <body>

        <script>
        function foo() {
            console.log("Hello World!");
        }
        </script>

      </body>
    </html>

  • outsourced / external file

      <!DOCTYPE html>
      <html>
        <body>

          <script src="myScript.js"></script>

        </body>
      </html>

  • full url

    <script src="https://www.foo/js/myScript.js"></script>

Comments​

Info:

  • It is most common to use single line comments.

    Block comments are often used for formal documentation.

  • line comment

    let x, y, z;    // Statement 1

  • block comment

    /* 
      block
      comment
    */