Javascript array length not working

Question

So I have this array:

[first_name: false, last_name: false, email: false, month: false, day: false, year: false, password: false, password2: false]

Now I if I do this console.log(arrayName.length) it will return 0; why? What I'm doing wrong?

//LE

This is how I do it:

var errors = {};
 $('.register-front').delegate('button','click',function(){
  var $this = $(this).parent().parent().parent();
  $this.find('input,select').each(function(){
    if(!$(this).val() || ($(this).val() == '-1'))
    {
      errors[$(this).attr('name')] = false;
    }
  });
  console.log(errors.length);
  return false;
 });

I made some changes but I still don't get it....

There are no associative arrays in JS. You should use an object (map) instead. — Fabrício Matté
– Fabrício Matté, Commented Nov 11, 2012 at 16:10
Use var errors = {}; to initialize your associative array (a.k.a. "plain object" in JavaScript lingo). — Šime Vidas
– Šime Vidas, Commented Nov 11, 2012 at 16:12
See my updated answer. You can use Object.keys(errors).length instead of errors.length. — Ted Hopp
– Ted Hopp, Commented Nov 11, 2012 at 16:28

Ted Hopp · Accepted Answer · 2012-11-11 16:27:29Z

8

Your notation seems odd. The square brackets are for an array, but the contents are object attribute/value notation. I don't think that will work. You can turn your expression into an object by replacing the [] with {}, but then, objects don't have length. You can get the number of keys in an object with:

Object.keys(obj).length

Alternatively, you can iterate through the object keys with:

for (var key in obj) {
    . . .
}

EDIT For the specific code you added, you can replace this line:

console.log(errors.length);

with:

console.log(Object.keys(errors).length);

edited Nov 11, 2012 at 16:27

answered Nov 11, 2012 at 16:09

Ted Hopp

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Marat Tanalin · Accepted Answer · 2012-11-11 16:09:00Z

0

In JavaScript, assotiative-array-like structure is Object:

{
    lorem: 'ipsum',
    dolor: 'amet'
}

In your example, replace square brackets with curly brackets, and you'll get such object.

answered Nov 11, 2012 at 16:09

Marat Tanalin

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Cecchi · Accepted Answer · 2012-11-11 16:12:20Z

0

That isn't an Array, an Array is a simple list of values where as this is a mapping of keys to values, i.e. an Object. You mean to do something like:

var myObject = { first_name: false, last_name: false, email: false, month: false, day: false, year: false, password: false, password2: false }

answered Nov 11, 2012 at 16:12

Cecchi

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