Passing arguments to javascript function
javascript, parameter-passing
Solution
A variable's scope is either the global scope (`window` in a browser) or a function.
In the first case `i` is defined in the scope containing the `for` loop. This is why it still changes until the end of the loop before the callback given to `setTimeout` is executed.
In the second case, the intermediate function contains and keeps another variable, `p`. Note that this would have worked without the test, as this would have been a different closure for each `setTimeout`.
Problem
Possible Duplicate: Javascript closure inside loops - simple practical example javascript variable scope/closure in loop after timeout Can you please explain step by step why the results are different? Snippet A (alerts 10) ``` for(var i=0; i<10; i++) if(i==3) setTimeout(function() {alert(i);}, 100); ``` Snippet B (alerts 3) ``` for(var i=0; i<10; i++) if(i==3) setTimeout((function(p) { return function() {alert(p);} } )(i), 100); ```