Validate form with jquery validation plugin

Question

I'm using jQuery Validation Plugin 1.9.0 (from http://bassistance.de/ ). The problem is that I can't figure out how to validate a text field only if a user type something in it. If the user did not write anything that field should not be treated as required.

Answer 1

Do not set the required rule option -

rules : {
     text1 : {
         required: false, // Or do not specify the option
         minlength: 3 // validation if it has value
     }
 },

Answer 2

if ( value != '' ) {
    // Do your validation here
}

Answer 3

You can pass a function to a validation rule. For instance

$("#demoForm").validate({
               rules: {
                    "requiredField": {sampleRule: function(e){
                                                var input = $(e); 
                                                if(input.val()) 
                                                    return true; 
                                                return false;
                                                }
                                        }                       
                },
                messages : {
                    "requiredField": "This field is invalid"
                }

Where "sampleRule" can be any rule you want eg. "required" or "minlength". The function gives the power to add conditional rule.