Trouble with Internet Explorer

The purpose of this article is to establish an uniform convention to deal with a very special issue of IE. It is for sure without this convention, websites would still run with or without problem. The issue is when IE passing null value from JavaScript to PHP, null value becomes string "null". If there is a possibility the user input could be "null", such as using "null" as login name or password, there is no way for PHP to detect which "null" is null and which "null" is input "null".

So, the accurate solution is never let JavaScript passing null to PHP, but using '' instead. It sounds easy; but JavaScript can generate null value without your knowledge. That is, if a parameter passing through a function to feed a form, when original parameter is undefined, eventually that undefined would be become string "null" or string "undefined" at the end of PHP. So, you would need to deal with every form input by special arrangement as follows:

; document.theForm.theInputItem.value = (parameter) ? parameter : ''

Then, to test if it is valid in JavaScript would be changed to:

; if (''!=parameter) {...}

At PHP end, it is relatively easy to detect if it is a valid input:

if (0!=strlen(trim(@$_POST["theInputItem"]))) {...};

However, for numeric data, it is not suitable to use '' instead null. It is still suggested to code as usual. The only difference is at PHP end:

if (0!=strlen(trim(@$_POST["theInputItem"])) && is_numeric(@$_POST["theInputItem"])) {...};


http://koncordpartners.blogspot.com/2009/12/test-various-nothings-in-php.html