Question

Regarding,
Local variables …

function foo(){var x = 1;  ...}

…and Global variables, …
(global, example 1)

function foo(){x = 1;  ...}

(global, example 2)

var x=1; function foo(){...}

…the only (simple) combination left is:

x=1; function foo{...}

… which I tested and noticed it also creates a global variable (like example 2), but is there any practical reason for this last example?
Note: I generally like to follow conventions and write readable code and stay away from ‘weirdness’.

Answer 1

It’s because JavaScript is a dynamic language. It allows you to use a variable without declaring it. You should always declare variables to eliminate confusion as you discussed. JSLint/JSHint will complain if you don’t.

Your “(global, example 1)” is wrong. that does not create a global variable.

function foo() { x = 1; }
function bar() { 
   alert(x);
}
foo();
bar();

edit i was wrong. http://jsfiddle.net/awuzA/