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Epicodus 1/20/21JavaScript & jQuery - 2


  • Function: A function is a block of code that performs an action and returns a result; optionally takes arguments
  • Comment: anything following // on a line in JavaScript is ignored by the computer. Comments are a convenient way to leave notes in your code for yourself or other programmers.


  • alert() opens a dialog box and returns undefined.
  • confirm() opens a dialog box and returns a boolean.
  • prompt() opens a dialog box and returns a string

Return Values

An argument is what you pass into a function or method; a parameter is a variable that's assigned to the argument. In the example below, number1 and number2 are parameters while 1 and 2 are arguments.

P*arts of a function*

  • function declaration starts with the function keyword.
  • Next comes the name. It should be descriptive and clear. In the example above, the name is add. Always use lower camel case for function names.
  • The name is always followed with parens. These parens may or may not include parameters. In the add function above, number1 and number2 are parameters.
  • The function body is enclosed in curly braces. The code inside the curly braces is the code that will be executed when the function is called.
  • Generally, you will want to return a value from your function. It's very common for beginners to forget the return, which means that the function will return undefined instead of a value. In the example above, the add function will return the value of number1 + number2.

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