JavaScript一线问题

Question

This code works:

$('[id$=lbl]').val() == "0" ? alert('Bla') : null;

but this codes don't:

$('[id$=lbl]').val() == "0" ? function(){alert('Bla'); return false; } : null;

$('[id$=lbl]').val() == "0" ? alert('Bla');return false; : null;

$('[id$=lbl]').val() == "0" ? return false : null;

i need "alert" after "return false"

How can I do that ?

Answer 1

don't know exactly what you're trying to do (and you missed to show the error-message to us - but why don't you simply use a "normal" if-statement like this (which has no effect on performace but is much more readable (my opinion) and easier to change (if you have to, in the future)):

if($('[id$=lbl]').val() == "0"){
  // do something
}else{
  // do something else
}

Answer 2

you have to do like this:

$('[id$=lbl]').val() == "0" ? function(){alert('Bla'); return false; } : null;

function(){alert('Bla'); return false; } function(){alert('Bla'); return false; } is just declaration of the function. Brackets will execute it:

do you mean that you need to do like this?:

function bla(){ return  ($('[id$=lbl]').val() == "0" ? (function(){alert('Bla'); return false; })() : (function(){return null;})() ); }

the function will return whatever expression will return... in this case and are both functions and they are returning some values(val1 -> false; val2 -> null;) and that value is returned by main(bla) function.

Answer 3

Do this:

var test = $('[id$=lbl]').val() == "0" ? false : null;
if (test === false) {
    alert('Bla');
    return false;
}

You can't return from within a ?: construct. Even if you could it would be a very confusing piece of code to read. Code is read far more often than it is written.

Better still if you're prepared to drop the ?: construct entirely use the answer from @oezi.

Answer 4

What you are doing is not practical:

$('[id$=lbl]').val() == "0" ? alert('Bla');return false; : null;

You can simply check its value like this:

alert($('[id$=lbl]').val());

To go real-world/practical, you should actually be doing:

var myvalue = $('[id$=lbl]').val() == "0" ? when true : when false;

Example:

var myvalue = $('[id$=lbl]').val() == "0" ? '' : $('[id$=lbl]').val();

Now myvalue will either be empty when it contains 0 or will have the value of the field specified. You can change off course according to your requirement.

Answer 5

$('[id$=lbl]').val() === 0