Question

I need to create a custom rule for the Jquery Validation Plugin that checks for one specific word.

In this case, the user must answer a question correctly by entering the word “cat” into the input field. The custom rule would need to define the answer as “cat”, I was thinking as a variable, and then check for it.

My failed attempt:

jQuery.validator.addMethod("answercheck", function(value, element) { 
  var password = string('hot');
  return value(password); 
}, "Type the correct answer");

and the setup:

rules: {
    input_answer{
        required: true,
        answercheck: true
    }

messages: {
    input_answer{
        required: "Answer the question",
        answercheck: "Your answer is incorrect"
    }

Any ideas?

Answer 1

As others have stated, this is not a secure method since anyone could see/manipulate the JavaScript and easily bypass it.

However, to simply answer your question, here’s how it’s done. (It’s also a good learning exercise about using addMethod)…

jQuery.validator.addMethod('answercheck', function (value, element) { 
    return this.optional(element) || /^\bcat\b$/.test(value);
}, "Type the correct answer");

And you also wouldn’t need to specify a message for answercheck below, because it’s already defined above within the method itself. (You were also missing some braces {, colons :, and a comma , in this code.)

rules: {
    input_answer: { // <- missing colon after input_answer
        required: true,
        answercheck: true
     }
}, // <- missing brace & comma
messages: {
    input_answer: { // <- missing colon after input_answer
        required: "Answer the question"
        //, answercheck: "Your answer is incorrect"  // not needed, specified in method
    } 
} // <- missing brace and maybe a comma depending on what follows

Working jsFiddle DEMO:

http://jsfiddle.net/ht8Lu/

---

As per the documentation, you’ll need to construct your own custom method.

Add a custom validation method. It must consist of a name (must be a
legal javascript identifier), a javascript based function and a
default string message.

Arguments:

name; String The name of the method, used to identify and referencing it, must be a valid javascript identifier

method; Callback The actual method implementation, returning true if an element is valid. First argument: Current value. Second
argument: Validated element. Third argument: Parameters.

message (Optional); String, Function The default message to display for this method. Can be a function created by
jQuery.validator.format(value). When undefined, an already existing
message is used (handy for localization), otherwise the field-specific
messages have to be defined.