Question

What is difference between

while(condition){
    var variable;   
    ...
}

and

while(condition){(function(){
    var variable;   
    ...
})();}

Can somebody explain me defference?

Answer 1

In the first case the variable is accessible anywhere inside the while (and even after it). In the second case it is private and accessible only inside the auto-invoking anonymous function. So the difference is basically in the scope of the variable. The second example seems pretty convoluted without providing more context.

First example:

while(condition) {
    var variable;   
    ... // the variable is accessible here
}

// the variable is accessible here

Second example:

while(condition) {
    (function() {
        var variable;   
        ... // the variable is accessible here
    })();

    // the variable is NOT accessible here
}

// the variable is NOT accessible here