In JavaScript, scope is kept within functions, but not within blocks (such as while, if, and for statements).
// Set a global variable, foo, equal to test
var foo = "test";
// Within an if block
if ( true ) {
// Set foo equal to 'new test'
// NOTE: This is still within the global scope!
var foo = "new test";
}
// As we can see here, as foo is now equal to 'new test'
alert( foo == "new test" );
// Create a function that will modify the variable foo
function test() {
var foo = "old test";
}
// However, when called, 'foo' remains within the scope
// of the function
test();
// Which is confirmed, as foo is still equal to 'new test'
alert( foo == "new test" );
