Question

when comparing string to see if it is empty, is there any difference between:

if($string==NULL){
    //do work
}

and

if($string==""){
    /do work
}

Just wondering beacuse I want to know which one is more effective in detecting blank input.

Answer 1

You’re kind of asking several vaguely-related questions here. PHP and JavaScript aren’t the same language, and you’re referencing different operators in the question title and body. In any event:

PHP:

'' == null          true
'' === null         false

JavaScript:

'' == null          false
'' === null         false

You might want to consider these tests for general “did I get something in this string variable”:

PHP:

if(!empty($string)) {
    // do work
}

JavaScript:

if($string) {
    // do work
}