JavaScript’s power lies in its well-defined syntax, a set of rules that govern how you write code. This structure ensures your instructions are clear and understandable to both you and the browser. Let’s delve into the fundamentals of writing JavaScript.Embedding JavaScript in HTML
Unlike many languages, JavaScript code can reside directly within your HTML using tags. These tags act as instructions for the browser to interpret the enclosed text as JavaScript code. You can place them anywhere in your HTML, but it’s generally recommended to keep them within the section for better organization.
Here’s the basic structure:
HTML
// Your JavaScript code here
Script Tag Attributes
While not always required in modern browsers, the tag can take two optional attributes:
- language: Traditionally used to specify the scripting language, typically set to “javascript”. This attribute is becoming less common.
- type: Defines the script’s MIME type, usually set to “text/javascript”. Modern browsers can often infer the type without this attribute.
Your First JavaScript Code
Let’s write some basic JavaScript to display “Hello World!” on the web page. We’ll use the document.write method to achieve this:
HTML
Your First JavaScript Program
document.write(“Hello World!”);
</body>
</html>
JavaScript Values
JavaScript works with two primary types of values:
- Literals: Fixed values directly represented in your code, like numbers (e.g., 10) and strings (e.g., “Hello”).
- Variables: Dynamic containers that store data and can change throughout your program. We’ll explore these in detail later.
Whitespace and Line Breaks
JavaScript generally ignores extra spaces, tabs, and newlines. This allows for flexible code formatting to improve readability. However, it’s good practice to maintain consistent indentation for better code clarity.
Semicolons (Optional but Recommended)
JavaScript statements typically end with a semicolon (;), just like in C/C++. While technically optional for single-line statements, using semicolons consistently enhances code readability and avoids potential errors.
Case Sensitivity
JavaScript is case-sensitive. This means name, Name, and NAME are treated as distinct entities. Be mindful of capitalization when writing variable and function names.
JavaScript Comments
Comments are annotations within your code that are ignored by the browser but provide valuable explanations for human readers. JavaScript supports both single-line (//) and multi-line (/* … */) comments similar to C/C++.
JavaScript Identifiers
Identifiers are names given to variables, functions, and other elements in your code. They must start with a letter (a-z, A-Z), underscore (_), or dollar sign ($), followed by letters, numbers, or underscores.
Operators
JavaScript provides various operators for performing operations on values. These include arithmetic operators (+, -, *, /), comparison operators (==, !=, <, >, etc.), and more. We’ll explore these operators in detail later.
Expressions
Expressions combine variables, values, and operators to create a result. For example, 10 + 20 is an expression that evaluates to 30.
Conclusion
This article provided a foundational understanding of JavaScript syntax. We’ll delve deeper into variables, data types, operators, control flow, and other essential concepts in the following chapters. Remember, consistent practice and exploration are key to mastering JavaScript syntax and building dynamic web applications.
Source: hashnode.com