Highlights of JavaScript — Form Validation and Event Handling

Highlights of JavaScript — Form Validation and Event Handling

To learn JavaScript, we must learn the basics.

To learn JavaScript, we must learn the basics.

In this article, we’ll look at the most basic parts of the JavaScript language.

We can add validation to select dropdown fields.

For example, we can write the following HTML:

<form onSubmit="return checkForSelection();">
  <select id="fruits">
    <option value="" selected="selected">
      SELECT A FRUIT</option>
    <option value="apple">apple</option>
    <option value="orange">orange</option>
    <option value="grape">grape</option>    
  <input type="submit" value="Submit Form">

And then add the following JavaScript:

const checkForSelection = () => {
  if (document.getElementById("fruits").selectedIndex === 0) {
    alert("Please select a fruit.");
    return false;

We added a select element and when we click on Submit Form, the checkForSelection function is run.

We add the return keyword so that we stop the default submit behavior and let the checkForSelection run.

javascript technology programming

What is Geek Coin

What is GeekCash, Geek Token

Best Visual Studio Code Themes of 2021

Bootstrap 5 Tutorial - Bootstrap 5 Crash Course for Beginners

Nest.JS Tutorial for Beginners

Hello Vue 3: A First Look at Vue 3 and the Composition API

JavaScript: Chessboard Program

Exercise from Eloquent JavaScript. Today, we will write a function that forms a chessboard. You can find the exercise in the Eloquent Javascript book (3rd edition, chapter 2; Program Structure). Write a program that creates a string that represents an 8×8 grid, using newline characters to separate lines. At each position of the grid there is either a space or a “#” character. The characters should form a chessboard.

Learning JavaScript: Development Environments for JavaScript Programming

One of the nice things about learning JavaScript these days is that there is a plethora of choices for writing and running JavaScript code. In this article, I’m going to describe a few of these environments and show you the environment I’ll be using in this series of articles.

Learning JavaScript: Data Types and Variables

To paraphrase the title of an old computer science textbook, “Algorithms + Data = Programs.” The first step in learning a programming language such as JavaScript is to learn what types of data the language can work with. The second step is to learn how to store that data in variables. In this article I’ll discuss the different types of data you can work with in a JavaScript program and how to create and use variables to store and manipulate that data.

[ Professor JavaScript ]: Introduction

Professor JavaScript is a JavaScript online learning courses YouTube Channel. Students can learn how to develop codes with JavaScript from basic to advanced levels through the online courses in this YouTube channel.

Hire Dedicated JavaScript Developers -Hire JavaScript Developers

Hire dedicated JavaScript Developers who are proficient in AngularJS, ReactJS, NodeJS, & VueJS frameworks. Get flexible hiring models as per your business requirements.