Validating forms with javascript

Question

 function validateText1() {
    var txt = document.getElementById("Surname");
    var a = txt.value.search(/^[a-zA-Z]{2,}$/);
    if (a != 0) {
        alert("Invalid Text.\n")

        return false;
    }
    else return true;
}

I came across this validation form, but I don't understand why is it a!=0 , shouldn't it be a==0 , since a number, representing the position of the first occurrence of the specified search value, or -1 is if no match is found.

Answer 1

Technically the search function tries to find text in a string, and returns the index of the first occurrence of the string.

For example:

var txt = "This is a funny string";

var resultIndex = txt.search("funny");

// resultIndex will return 10

If it is not found, it will return -1.

It should really be if (a >= 0), but the above will work too.

Answer 2

It's a != 0 because it's testing for a failing search, which is when it reports "Invalid input" and returns false . a == 0 would mean that the search found a match, and in that case the input is valid and it returns true .

Answer 3

The search indicates it will return the index at which position the match starts, so if it doesn't start at 0 it means a special character is used.

Altho I would never use this to validate my forms. Matching names is pretty hard.