I tried to convert snippet 1 to snippet 2 but this did not work (the text fields did not clear). f3aa and f3bb are each text fields that I need to clear after a sumbit.
Snippet 1
var target=document.getElementById('f3aa');
target.value='';
var target=document.getElementById('f3bb');
target.value='';
Snippet 2
o1('f3aa')=o1('f3bb')='';
Snippet 3
function o1(a)
{
document.getElementById(a);
}
Assuming I've understood your question correctly, you were nearly there:
document.getElementById('f3aa').value = '';
document.getElementById('f3bb').value = '';
In your snippet 2, you are trying to assign an empty string to a DOM element, rather than the value property of that element.
In snippet 1, you assign a DOM element to the target variable, and then assign an empty string to the value property of the target variable. As target contains a DOM element, you assign that string to the value property of that element, which is equivalent to the code I have shown above.
You forgot to include the attribute names from your first snippet in your second:
document.getElementById('f3aa').value='';
document.getElementById('f3bb').value='';
(Note that this isn't really an "optimization" - there will be no noticeable difference in how quickly the two snippets run. Use whichever is more readable.)
X('f3aa').value = X('f3bb').value = '';
where X is your query-by-ID implementation.
Live demo: http://jsfiddle.net/zmr29/
(I wrote a X function in my demo, but I assume that you either use a library or have some other shorthand for DOM queries.)
o1('f3aa').value = o1('f3bb').value = '';I think it's illegal to use var to declare a variable more than once in the same scope.
This code is bad:
var test = true;
var test = false;
This code is good:
var test = true;
test = false; // <-- no "var" keyword here
test value with the second. Your second example creates a global test variable that is shadowed by the local test (assuming we're in a function).:)