If you declare a variable, using "var", within a function, the variable can only be accessed within that function. When you exit the function, the variable is destroyed. These variables are called local variables. You can have local variables with the same name in different functions, because each is recognized only by the function in which it is declared.
If you declare a variable outside a function, all the functions on your page can access it. The lifetime of these variables starts when they are declared, and ends when the page is closed.
More Examples
Function with a parameter
How to pass a variable to a function, and use the variable in the function.
Function that returns a value
How to let a function return a value.
Loops execute a block of code a specified number of times, or while a specified condition is true.
JavaScript Loops
Often when you write code, you want the same block of code to run over and over again in a row. Instead of adding several almost equal lines in a script we can use loops to perform a task like this.
In JavaScript, there are two different kind of loops:
- for- loops through a block of code a specified number of times
- while- loops through a block of code while a specified condition is true
