Form validation in meteorjs - meteor

Question

I am doing simple validation of inputs in meteorjs, after first tour it works, and every next time it doesn't work (until I reload the page) – it means error messages are not displayed.
//main.js//
Template.addMealForm.events({
'click #submitNewMeal': function (ev) {
ev.preventDefault();
var query = {
name: $("#name").val().trim(),
price: $("#price").val(),
calories: $("#calories").val(),
category: $("#category").val()
};
areInputsValid(query);
}
});
var areInputsValid = function (query) {
if ((query.name.length === 0) || (query.price.length === 0) || (query.calories.length === 0)) {
$("#warningLabel").addClass("di")
$(".warningLabel").text("All fields are required");
}
else if ((isNaN(query.price) === true) || (isNaN(query.calories) === true)) {
$("#warningLabel").addClass("di")
$(".warningLabel").text("To Price and Calories fields please enter a number");
}
else {
console.log('it works');
$('.dn').hide();
}
};
//main.html//
<template name="addMealForm">
<form role="form">
<div class="form-group">
<label for="name">Name</label>
<input type="text" class="form-control input_form" id="name" placeholder="Name of the meal">
</div>
<div class="form-group">
<label for="price">Price</label>
<input class="form-control input_form" id="price" placeholder="Price">
</div>
<div class="form-group">
<label for="calories">Calories</label>
<input class="form-control input_form" id="calories" placeholder="Calories">
</div>
<div id="warningLabel" class="form-group has-error dn">
<label class="control-label warningLabel"></label>
</div>
<button id="submitNewMeal" type="submit" class="btn btn-rimary">Add</button>
</form>
</template>

Answer 1

The problem is that you are calling $('.dn').hide() in the success case. Because #warningLabel has a class of dn it will not be displayed again on subsequent errors.
One solution is to add $('.dn').show() to the top of areInputsValid.

Answer 2

You already have Tracker as part of Meteor, so I put a little tutorial and JSfiddle together on how to use it to implement a typical form validation scenario.
http://bit.ly/meteor-form-validation-video
http://bit.ly/meteor-form-validation-fiddle