How do I determine if a field is empty or null in a Javascript Array?

Question

My objective is to determine if a field called name is empty.
My code is returning this error:

"object is not a function'.

This is resolved because I initially used (name) not [name] in the ifstatement

function notEmptyOrNull() {
    var name1 = "Sherlock";
    var name2 = "Watson";
    var name3 = "";

    var namesArray= ["Ben", "Lucy", "Watson", "Sherlock"];

    if  (namesArray[name1] !== null) {  // resolved error

        console.log(name1);
        return true;
    }
    return false;
}
notEmptyOrNull();

Updated the code:
if (namesArray(name) to if (namesArray[name] which resolved the error.

But when I tested for name3 which I have changed to an 'empty string' = ""

How do I do this ?

In Chrome Dev Tools I would like to see output as true or false for each.

I would also like to output the data of each field.

Again, this is rather simple but I am still sorting this out.

I know that I'm missing sections of the code to accomplish this.

An array is not a function, you can't do namesArray() (except in old IE), you do namesArray[name1] ! — adeneo
– adeneo, Commented Mar 18, 2015 at 16:58
And you probably want if ( namesArray.indexOf(name1) === -1 ) anyway — adeneo
– adeneo, Commented Mar 18, 2015 at 16:59
wow. that was quick and an easy fix. I am trying to do this for name2 which i renamed with a typo to return false. thanks. — shareyourpeace
– shareyourpeace, Commented Mar 18, 2015 at 17:01
@adeneo you said this "And you probably want if ( namesArray.indexOf(name1) === -1 ) anyway " and yes I do want to make use of indexOf(). But when I used this code, I am not getting any output in the console ! — shareyourpeace
– shareyourpeace, Commented Mar 18, 2015 at 17:12

Amr Elgarhy · Accepted Answer · 2015-03-18 17:00:18Z

1

What about namesArray.indexOf(name1) > -1 Like this you are not checking for null, you are checking if the value exist in the array

answered Mar 18, 2015 at 17:00

Amr Elgarhy

69.2k70 gold badges193 silver badges312 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Hoijof · Accepted Answer · 2015-03-18 16:59:21Z

0

You're calling the array values wrongly. The "()" are used for calling functions, to get an element from an array you have to use "[]"

Like this:

if  (namesArray[name1] !== null) {

P.D. In fact what I think that you want is to find if the name is INSIDE the array, in which case you should use this method:

if (namesArray.indexOf(name1) !== -1)

You can check the documentation here

answered Mar 18, 2015 at 16:59

Hoijof

1,43316 silver badges27 bronze badges

3 Comments

Radio Over a year ago

wont this still fail as it's not an associative array. There needs to be an indexOf function to search the array.

shareyourpeace Over a year ago

@adeneo This thread took a turn. My original question was to test ' if name is null'. The thread began to suggest ways to test 'if name exists in the array. Your original response is correct but I cannot click on an arrow to upVote your answer. also. When I change this field to be an empty string name1 = "" I am 'not returning -1 or false in the console.' Do you or does anyone know why ?

shareyourpeace Over a year ago

@JLRishe hi. if you have a chance can you view this post, especially the post directly above this one by me. thanks.

UnJavaScripter · Accepted Answer · 2015-03-18 17:03:27Z

0

Use Array.indexOf()

Replace:

 if  (namesArray(name1) !== null) { ...

With:

 if  (name1.indexOf(namesArray) !== -1 ) { ...

Array.indexOf() will return -1 if the element can't be fount in the array or else, the index of the element inside the array (where 0 represents the first element).

answered Mar 18, 2015 at 17:03

UnJavaScripter

8006 silver badges6 bronze badges

Collectives™ on Stack Overflow

How do I determine if a field is empty or null in a Javascript Array?

3 Answers 3

Comments

3 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

3 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related