In a book trying to illustrate global/local variable scope it used this example to convey the concept:
test();
if (isset(bar)){
alert('bar must be global!');
}else{
alert('bar must be local!');
}
function test(){
var foo = 3;
bar = 5;
}
function isset(varname){
return typeof varname != 'undefined';
}
Right now the if returns the alert 'bar must be global.', which makes sense because the variable passed to the isset(), bar, in this case is global. But why doesn't the if statement return the alert('foo must be local'); when you pass lets say when you pass foo in the isset function.
Since you haven't used the var keyword, the variable is defined on global scope and still exists after executing test function. This is explained more thoroughly here.
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