Javascript Statements

Defining Javascript Statements

• Variable statements
• Condition statements
• Function declarations

Variables Assignment in Javascript Statements

var number;
number = 5;

Explanation of Javascript Statements Syntax

keyword(arguments);

alert("Hello, World!");

Javascript Conditional Statements

Comprehensive Guide to Javascript Conditional Statements

• If Statement
• If...else Statement
• Switch Statement

Javascript Conditional Statement Examples

if (5 > 3) {
    alert("Five is greater than three.");
}

if (5 < 3) {
    alert("Five is less than three.");
} else {
    alert("Five is greater than three.");
}

var fruit = "Apple";

switch (fruit) {
    case "Banana":
        alert("This is a banana.");
        break;
    case "Apple":
        alert("This is an apple.");
        break;
    default:
        alert("This is not a banana or an apple.");
}

Digging into the Print Statement in Javascript

How to Use Print Statement in Javascript

Print Statement in Javascript Examples

alert("Hello, World!");

console.log("Hello, World!");

document.write("Hello, World!");

In-depth Look at Break Statement in Javascript

Functions and Usage of Break Statement in Javascript

• To end a loop prematurely, skipping the remaining iterations.
• To exit from a case in a switch structure.

Break Statement in Javascript with Examples

for (let i = 0; i <= 10; i++) {
    if (i == 5) {
        break;
    }
    console.log(i);
}

var color = "Red";
switch (color) {
    case "Blue":
        alert("Color is Blue."); 
        break;
    case "Red":
        alert("Color is Red."); 
        break;
    default:
        alert("Color is neither Blue nor Red."); 
}

Practical Application of Javascript Statements

Showcasing Real-Life Javascript Statements Examples

var username = document.forms["RegForm"]["Name"];
var email = document.forms["RegForm"]["EMail"];

if (username.value == "") {
    window.alert("Please enter your name.");
    username.focus();
    return false;
}

if (email.value == "") {
    window.alert(
      "Please enter a valid e-mail address.");
    email.focus();
    return false;
}

var i = 0;
var images = [];
var time = 3000;

images[0] = 'image1.png';
images[1] = 'image2.png';
images[2] = 'image3.png';

function changeImg(){
   document.slide.src = images[i];

   if (i < images.length - 1){
     i++;
   } else {
     i = 0;
  }

  setTimeout("changeImg()", time);
}

window.onload = changeImg;

Best Practices When Writing Javascript Statements

• Prioritise readability: Use proper indentation, consistent naming conventions, and include comments to describe what your code is doing. This not only benefits others who may look at your code, but it also helps you, especially when you need to revisit a code you wrote a while back.
• Keep it simple: Write small, simple functions that do one thing. If a function does too many things, it becomes harder to understand, debug, and maintain.
• Avoid using global variables: They can be altered anywhere in your code, making debugging incredibly complicated. Use local variables whenever possible.
• Always declare variables: Javascript will allow you to use a variable without declaring it first, automatically making it a global variable. To prevent this, always declare your variables with the 'var', 'let', or 'const' keywords.
• Validate user input: Never trust data provided by users. Always validate and sanitize user inputs to protect your site from malicious code.