I am using this jquery plugin: http://docs.jquery.com/Plugins/Validation
and I want to write a conditional statement.
If the user leaves a specific form field blank, then the field is not required. However, if they don't leave it blank, then it must start with a number
For the "must start with a number" part, I think you'll need a custom rule.
For the "required if another field is not empty" part, you can use a dependency expression to decide if it's required when the validator runs:
Put them together and you'll have something like this:
<form>
<input name="first">
<input name="second">
</form>
$.validator.addMethod("startsWithNum", function(input, element) {
// First char must be digit if not empty
return ! input || input.match(/^[0-9]/);
}, "This field must start with a number");
$('form').validate({
rules: {
first: {required : true},
second: {
"startsWithNum" : true,
required: function() {
// required if <input name="first"> is not empty
return $('[name="first"]').val() !== '';
}
}
}
});
Demo: http://jsfiddle.net/qCELA/2/
There is only a single input in the form I need to make. If the user left it blank, then no rules apply. Otherwise, that single input field must start with a number.
If you only have one input field, the custom rule is all you need:
$('form').validate({
rules: {
second: {"startsWithNum" : true}
}
});
startsWithNum, see edit.