Validate-js is a project mainly written in JavaScript, it's free.
Simple JavaScript validation
var validate = new Validate(
{
name: {
pattern: /^.{8,}$/
},
occupation: {
pattern: /^.{20,}$/,
required: true
}
},
{
name: 'Mal Reynolds',
occupation: 'Captain Tight Pants'
}
);
if(!validate.isValid){
console.log(validate.failed.join(', '));
}