Returning true or false from javascript function

Question

I'm doing a regex check on a string within a function:

function ValidateZipCodeString(listOfZipCodes) {
    var regex = /^([, ]*\d{5})+[, ]*$/,
    matches = regex.exec(listOfZipCodes);

    if (regex.exec(listOfZipCodes) === null) {
        console.log('validation failed');
        return false;
    } else {
        console.log('validation passed');
        return true;
    }
}

The regex is correctly detecting a valid/invalid list of zip codes.

I'm calling the function with this:

console.log('zip code: ' + listOfZipCodes);
if (ValidateZipCodeString(listOfZipCodes)) {
    $tr.find('label#lblCoverageEditError').text('There is invalid text in the list of zip codes. Only 5-digit zip codes allowed.').show();
} else {
    console.log('validate function returned true');
}

The problem is that the above if/else goes to the else clause, when the console output within the validation function shows "validation failed". So I must not be calling that function right.

What's the correct way to do what I'm trying to do?

Answer 1

Your function could be greatly simplified to:

function ValidateZipCodeString(listOfZipCodes) {
    var regex = /^([, ]*\d{5})+[, ]*$/;

    if (regex.test(listOfZipCodes)) {
        console.log('validation passed');
        return true;
    } else {
        console.log('validation failed');
        return false;
    }
}

...or:

function ValidateZipCodeString(listOfZipCodes) {
    var regex = /^([, ]*\d{5})+[, ]*$/;
    return regex.test(listOfZipCodes);
}

...or even just:

function ValidateZipCodeString(listOfZipCodes) {
    return /^([, ]*\d{5})+[, ]*$/.test(listOfZipCodes);
}

...but the real issue (as Teemu points out) is not in your function, but in the use of it. Your function answers the question, "Is this a valid zip code string?", but your use of it is saying, "Say this is invalid if my function says it is."