if.. comparison.. What is -1 1

[sdi]

I have read and read and just am not getting it. What exactly is -1 telling me?

Example 1:

if(navInfo.indexOf("Win98" != -1))
{
//do something
}

Example 2:

var myString = "something old, something new, you know the rest"
var foundAtPosition = 0;
var myCount = 0;
while(foundAtPosition != -1)
{
foundAtPosition = myString.indexOf("something", foundAtPostion);
if(foundAtPosition != -1)
{
myCount++;
foundAtPosition++;
}
}

document.write("There are " + myCount + " occurances of something"
}


Thank you in advance,

Brian

 

[jpbrassard]

The JavaScript function indexOf searches a string for a specified substring, and returns the character position where the substring is first found. If the substring is not found, it returns a -1. The comparisons in your script block examples are testing to see if the substring is found by checking that the return from various indexOf calls are not -1.

Found this information at

http://devedge.netscape.com/library/manuals/2000/javascript/1.5/reference/string.html#1196895.

HTH,
jp

 

[sdi]

Thank you for the reply. I think I am beginning to grasp it.

**If the substring is not found, it returns a -1**

That put it all in prospective for me and the link will be quite handy in the future.

Again, Thank you!

Brian