JS function with jquery always return undefined

Question

I am building a Js function with Jquery checking if certain inputs are empty or not for validation. Here's the function that checks if the inputs are empty or not:

   function isValid(elements){
      var validation = false
      elements.each(function() {
        if ($( this ).val().length > 0){
          validation = true
        }
        else {
          validation
        }
      });
      validation
    }

however whatever I do my function returns undefined and never the boolean value that is supposed to be contained in the validation variable ?

What should I do for my function to return true or false ?

What do you think `validation` lines are doing? Your logic is also flawed. The validation is most likely not doing what you want it to do. — epascarello, Jul 26 '16 at 15:53
indeed I thought the my last validation was returning my boolean value but now I understand I need to use return — David Geismar, Jul 26 '16 at 17:05

score 2 · Answer 1 · edited May 23 '17 at 11:53

2

Your function isValid() is returning undefined because this is the expected behaviour in JavaScript: undefined is the “default” returned value if a function does not specify one returned value, and your function isValid() doesn't have any return.

Check this answer.

edited May 23 '17 at 11:53

Community

1
1

answered Jul 26 '16 at 15:37

Gerardo Furtado

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Olivier Boissé · Accepted Answer · 2016-07-26T15:43:51.617

2

You can return false if at least one element is empty, otherwise return true.

function isValid(elements){
  var validation = true;

  elements.each(function() {
    if ($( this ).val().trim().length === 0){
      validation = false;
    }
  });

  return validation;
}

edited Jul 26 '16 at 15:43

answered Jul 26 '16 at 15:39

Olivier Boissé

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return false inside of `each` would act as a breaking statement – Rajaprabhu Aravindasamy Jul 26 '16 at 15:40
You may also want to add a `trim()` in the length check, otherwise filling the field with spaces would be valid – Rory McCrossan Jul 26 '16 at 15:42

score 2 · Answer 3 · answered Jul 26 '16 at 15:44

You can do your code like below by using Array#some,

function isValid(elements) {
 return !Array.from(elements).some(function(itm){ itm.value.trim().length == 0 });
}

You are not at all returning anything from the function, that means as a default returning value undefined will be returned.

JS function with jquery always return undefined

3 Answers3