CODEWITHSUNDEEP
javascriptreturn-value
marky
marky

Reputation: 5068

Returning true or false from javascript function

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?

Upvotes: 4

Views: 74386

Answers (3)

Christophe
Christophe

Reputation: 28114

Others correctly pointed out that you just had your tests in the wrong order. However, and more importantly, your regex is incorrect, as it will for example return true for "1234567890".

Here is a suggestion:

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

Upvotes: 2

Grinn
Grinn

Reputation: 5528

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."

Upvotes: 7

Teemu
Teemu

Reputation: 23396

Actually your validation function doesn't return true when validation fails. You just check the value incorrectly, it should be:

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');
}

Upvotes: 5

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