Como os Sites Sabem Que um Campo Está Vazio? | Validação de Formulários com JavaScript

🎥 Want to watch the full lesson, including the live development process? Original live stream: https://youtube.com/live/t6E9vCj7_Q8 💡 How do websites know if you left a field empty or entered incorrect information? In this video, we'll build a complete registration system and understand how form validation with JavaScript works in practice. In addition to the project, you will learn: ✅ if and else in practice ✅ Why forms use multiple if statements ✅ getElementById ✅ classList.add ✅ querySelectorAll ✅ forEach ✅ Checkbox and Select ✅ How to display error messages ✅ What the small tag is for ✅ How to automatically clear errors ✅ Minimum age validation ✅ How websites block invalid data Chapters 00:00 How Do Websites Block Incorrect Data? 01:52 Getting to know the project 03:30 What is the small tag for? 06:33 Capturing elements with getElementById 13:36 Creating the validations 19:37 Validating minimum age 22:09 Validating Select and Shift 24:44 Validating Checkbox 26:35 Displaying success messages 29:11 Testing the form 33:14 Creating the clearErrors() function 34:21 querySelectorAll in practice 35:34 forEach to iterate through the fields 38:39 Final result of the project At the end of the lesson you will have a form similar to those used in real systems. 🔥 Zero’s JavaScript Playlist:    • JavaScript do ZERO ao Intermediário | Tril...   #javascript #programming #frontend #webdevelopment #javascriptdozero