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Jan 18.2011

Restarted my JS studies coz it was doing my head in :p

Can some please explain this for me?

[CODE]
if(email.indexOf(“@”) != -1){ alert(“You have an @ in your email address”); }[/CODE]

This code produces an alert if there is an @ in the input field. BUT… Why the != -1? Why not? == 1? I tried… It doesn’t work. It only works if I go, == 0

Just looking for an explanation as to why. Thanks in advance folks
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4 Comments(s) ↴

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@WolfShadeJan 18.2011 — -1 equals "false".

If there is not an index (0 or greater) then it doesn't exist, so the function returns -1.

^_^
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@Hooded_VillianauthorJan 18.2011 — -1 equals "false".

If there is not an index (0 or greater) then it doesn't exist, so the function returns -1.

^_^[/QUOTE]

I see... And why does JS have to be so annoying as to be written like that. LoL.

I checked on http://www.w3schools.com/jsref/jsref_IndexOf.asp aswell, and it appears that indexOf() returns a number. So, exactly as you said, a positive number would be true and a negative, in this case -1, would be false.

Thanks WolfShade
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@WolfShadeJan 18.2011 — No problem.

And the reason why it's like that is because it uses a 0-based index (the first position is 0) instead of a 1-based index (first position is 1.)

^_^
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@Hooded_VillianauthorJan 18.2011 — No problem.

And the reason why it's like that is because it uses a 0-based index (the first position is 0) instead of a 1-based index (first position is 1.)

^_^[/QUOTE]

I see... Kind of like arrays? Starts at 0.

var myName = new Array();

myName[0] = "Alexis";

etc

So, if I said... indexOf("@") == 0, that would still be positive, provided an @ was found.

Thanks again...
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