if( str.indexOf(" ") !== -1 )

[Ken Guie]

So I needed some code to prevent someone from entering spaces into a web app I was building as a training exercise.

I came across this on Stackoverflow:

if( str.indexOf(" ") !== -1 ) {
and I added alert("Please enter a value.")
}

It works but I'm not sure what this line actually translates too.

Is it that all spaces have a value of -1? But then again, this line is asking for when it is Not -1 right?
Quoted spaces are strings correct? " " is a string.
What are we actually saying?

Thanks

[Matthew Brown]

Hi Ken. Welcome to the Ranch!

Have you looked at the documentation for the indexOf method? For example, http://www.w3schools.com/jsref/jsref_indexof.asp.

You'll see it returns -1 if the search string is not found (otherwise it returns the position it was found at). So that condition is checking for whether str contains a space or not.

[Bear Bibeault]

Welcome to the Ranch.

Let me introduce you to MDN (Mozilla Developer Network) and its documentation of String.

Look up the definition of the indexOf() method to find out what it does and why -1 is special.

[Edit: Doh! Beat by mere seconds to the draw!]

[Bear Bibeault]

(While w3schools has improved, I still prefer MDN as a resource).

[Ken Guie]

Thanks, Good tools!

I've used them before but I didn't think to look it up.

I just ran across this site and i thought i'd join and ask.

Thanks a lot !

[Bear Bibeault]

Glad to have you!

And yes, in JavaScript either double or single quotes delimit a string.