Validating forms in HTML, PHP, and JavaScript

Question

If I am defining a function in JavaScript at the top of my page that validates if the string entered in a form is (A-Z,a-z, or 0-9). And then I call that function when they submit it saying :

onsubmit="return Validator(this);"

If the function name is :

function Validator(form)

Why isn't it actually validating the string submitted when we actually click on submit, and is there a better way of validating forms?

Answer 1

Almost certainly because the Validator function is not written correctly… but since you haven't shown us what it looks like, we can't say specifically why.

Perhaps it is expecting a String and you are giving it an HTMLFormElement.

Answer 2

You aren't submitting a string to Validator, you are submitting an input element. So you would do if(form.element.value != "") ... or something... And yes there is a better way

Answer 3

An onsubmit handler function needs to return false to cancel the event (form submission) if you want to not submit and show a validation error message instead.

Plain Javascript approaches:
http://stackoverflow.com/questions/967483/form-is-still-submitted-even-though-listener-function-returns-false

jQuery approaches:
http://stackoverflow.com/questions/665470/how-to-not-submit-a-form-if-validation-is-false

Answer 4

Lots of options for form validation. Depending on your framework, you may want to use Jquery's validation. If you go with yui, I have submitted a form validator that will be useful

Here is the gallery submission, from thee you can look at examples