Validation plugin, using jQuery for plugin and Underscore mixins for functionality.

jQueryValidator.js

// In Router.js, whatever route needs validation
Router({
  //Blahblahblah
  somePage : function(e) {
    // Build all the things!
    var SomeModule = zngine.module('someModule')
    var ThisView = new SomeModule.SomeView( someParams )
    ThisView.render()
  }
  
})

// In SomeModule.js
SomeModule.SomeView = Backbone.View.extend({
  el : 'blah',
  events : {
    'click #thisIsTheButtonToEnableWhenValidationPasses' : 'doForm'
  },
  validatorConfig : {
    submitButton : '#thisIsTheButtonToEnableWhenValidationPasses',
    fields : {
      'fieldName' : {
        selector : '#FieldSelector',
        msg : 'This is the error message to display beneath the input on failed validation.',
        validators : {
          isString : true, // Explicit Underscore method names
          size : {
            min : 4,
            max : 10
          },
          noNumbers : true
        }
      }
    }
  },
  initialize : function() {},
  render : function() {
    // Build all the things!
    this.$el.validator( this.ValidatorConfig )
  },
  doForm : function(e) {
    // Process form normally
  }
})

// jQuery Plugin
$(function() {
  $.validator({
    submitButton : '#thisIsTheButtonToEnableWhenValidationPasses',
    'fieldName' : {
      selector : '#FieldSelector',
      msg : 'This is the error message to display beneath the input on failed validation.',
      validators : {
        isString : true, // Explicit Underscore method names
        size : {
          min : 4,
          max : 10
        },
        noNumbers : true
      }
    }
  }, model, context)  
})

ProgrammaticValidator.js

// In Router.js, whatever route needs validation
View({
  events : {
    'click #submit' : 'someFunction',
    'click #another' : 'anotherFunction'
  },
  
  //Blahblahblah
  validate : function(success, error, context) {
    _.validate( this.validatorConfig, this.model.toJSON(), success, error, context )
  },
  
  someFunction : function(e) {
    e.preventDefault()
    this.validate(function() {
      // Success
    }, function() {
      // Failure
    }, this)
  }
  
})

// jQuery Plugin
_.mixin({
  validator : function(config, model, context) {
    // Stuff here
  }
})