Test for array containing a single empty string in JavaScript

Question

I am returning an array from a function in JavaScript and I need to be able to know when it contains nothing but a single empty string. When I print that value to the console, it returns this:

[""]

I get an error if I do the following:

if(myVar == [""]){
    // do something
}

How can I test for that value in that variable? jQuery answers are perfectly acceptable as well as plain JavaScript.

You should not get an error when doing myVar == [""]. What's the error? — Felix Kling
– Felix Kling, Commented Oct 13, 2014 at 18:06

PeterKA · Accepted Answer · 2014-10-13 17:57:08Z

4

I would use:

if( myVar instanceof Array && myVar.length === 1 && myVar[0] === '' ) {
// ....
}

edited Oct 13, 2014 at 17:57

answered Oct 13, 2014 at 17:42

PeterKA

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1 Comment

blex Over a year ago

typeof myVar will return "object", so this won't work. Use myVar instanceof Array instead ;)

robot9706 · Accepted Answer · 2014-10-13 17:47:28Z

1

if (myVar.length == 1 && myVar[0] == ""){   
}

edited Oct 13, 2014 at 17:47

answered Oct 13, 2014 at 17:41

robot9706

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3 Comments

KooiInc Over a year ago

What if myVar is ['',1,2,3]

robot9706 Over a year ago

Edited, now it works if the array only contains strings.

jfriend00 Over a year ago

You should change == to ===.

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