What is a function?

Built-in functions

• alert
• String.prototype.indexOf
• String.prototype.length
• Array.prototype.forEach
• Array.prototype.map

Anonymous functions

Parameters and return value

Function scope

Exercises

1. Define a function with a parameter of name. Say hi to the name in the function.
2. Define a function with a parameter of n. Caculate the sum of numbers from 1 to n, and return the sum.