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JavaScript JavaScript Foundations Strings Methods: Part 1

Posted by Timothy Crandall
Timothy Crandall
4,354 Points

What is the significance of !==-1 here?

if(whole.indexOf("W") !==-1) {
console.log("W exists in string")
} else {
console.log("W does not exist");
}

I am a little confused about what !==-1 means in this statement. I know it literally means does not equal -1, but how does this little piece relate to the big picture (this if/ else function)? I can put anything in there it seems and it returns as W exists, but when I do not include anything after ("W"), I receive the else statement. Can anybody describe what is happening here? Thank you!!

1 Answer

Dave McFarland
STAFF
Dave McFarland
Treehouse Teacher
Dave McFarland
Dave McFarland
Treehouse Teacher

You use the indexOf() method to see if one or more letters exists in a string. So whole.indexOf("W") searches the string contained in the variable whole for the letter "W". If indexOf() finds a match it returns a number indicating where in the searched string the match occurs, with 0 being the first letter of the string and 1 being the second letter of the string, and so on.

If no match is found indexOf() returns -1. So the if/else statement you wrote basically looks for 'W' in the string. If it is there indexOf() will return a value of 0 or more. If it's not there, indexOf() returns -1 or no match.

Timothy Crandall
Timothy Crandall
4,354 Points

Thank you that helps me a bit!