Javascript Syntax
JavaScript syntax refers to the set of rules that define the structure and organization of JavaScript code. It includes elements such as variables, operators, and control structures, and follows a specific format for writing commands and instructions. Understanding and adhering to JavaScript syntax is crucial for writing functional and error-free code in web development and other applications.
3 Key excerpts on "Javascript Syntax"
- Kenneth J. Luterbach(Author)
- 2018(Publication Date)
- Routledge(Publisher)
...Technically, as discussed in Section 3.1.4, such commands are calls to subroutines, which many programmers also refer to as functions or methods. In the Spider-Monkey version of JavaScript, we use print for output and readline for input. Other programming languages are similar in this regard. For example, the Pascal programming language uses write for output and readln for input; Perl uses print for output and <stdin> for input; BASIC and Python use print for output and input for input. To summarize this section, we have written interactive programs in JavaScript to obtain the user’s name and the user’s response to a question. Those programs have revealed that computer programs contain variables and statements. The fundamental building blocks of computer programs are variables, statements, and data structures. Once you know those fundamental building blocks, you can combine them in unique ways to express yourself creatively and to engage in problem solving. Note that variables contain information, which we generally refer to as data. Each variable contains one particular type of data. With knowledge of three data types and the skill to use three types of statements, three data structures, and one technique, you will be able to program a computer for general purpose problem solving and creative expression. 3.1.2 Three Data Types In JavaScript programming, a variable can be a number, a character string, or a Boolean value. A Boolean value is either true or false. The Boolean type is named after George Boole, an early nineteenth-century mathematician and philosopher, who developed Boolean algebra or Boolean logic. As an aside, Boolean algebra offers a set of 16 propositions based on two variables (x and y), each of which is either true or false...
eBook - ePub- Mike McGrath(Author)
- 2020(Publication Date)
- In Easy Steps Limited(Publisher)
...Standard JavaScript objects, such as functions, call an internal constructor function to create the object by defining its components. Don’t worry if you can’t immediately understand how closures work. They can seem mystical at first, but will become clearer with experience. You can continue on and come back to this technique later. Summary • JavaScript code can be included in an HTML document directly or from an external file using <script> </script> tags. • JavaScript can display output in an HTML element in an alert dialog box or in the browser’s console window. • JavaScript statements may contain keywords, operators, values, and expressions. • The JavaScript interpreter ignores tabs and spaces. • JavaScript statements can be grouped in { } curly bracket function blocks that can be called to execute when required. • Variable and function names may comprise letters, numbers, and underscore characters, but must avoid keywords. • JavaScript variables may contain data types of String, Number, Boolean, Object, Function, Symbol, null, and undefined. • Variables declared with the let keyword can be reassigned new values, but the const keyword does not allow this. • A function expression has statements grouped in { } curly brackets for execution, and it returns a final single value. • The () parentheses of a function expression may contain parameters for argument values to be...
eBook - ePubConfident Web Design
Master the Fundamentals of Website Creation and Supercharge Your Career
- Kenny Wood(Author)
- 2018(Publication Date)
- Kogan Page(Publisher)
...This way the user will see the page render quicker than if the script tags were placed in the middle of the HTML tags. Using the <script> tags is a nice and easy way of getting your code to execute, but it’s not the only way. Using script tags can get quite messy, especially if we have a lot of JavaScript code to run. Your HTML page can end up getting very long and confusing, not to mention difficult to navigate if you include all of your script directly on the page. Like with CSS, this is where using external files comes into practice. As with CSS we can create a separate file (in this case with a.js file extension), which we can point a reference to and our webpage will then find and include the file for us, just like we do with our external stylesheets. Scripts are loaded using the following snippet: <script src=”script.js”></script> Where you place this script tag will determine where your code is executed just like with placing your <script> tag. Likewise, you should be aiming to place your script reference at the bottom of your body for the best performance possible. Just like with image files, your path to your script in the reference can be be either an absolute or a relative link. Syntax JavaScript is a fantastic programming language, and what’s more, it’s actually fairly easy to pick up the basics relatively quickly. So let’s now take a look at how we structure our JavaScript. JavaScript statements A JavaScript statement is comprised of: values; operators; expressions; keywords; and comments. Values JavaScript values are simply pieces of data. Each value, or piece of data, has a type. That type defines the type of content that we are expecting. There are six different basic types for values. They are: numbers; strings; Booleans; objects; functions; and undefined values. Numbers As you might have guessed, a value with a ‘number’ type is a value formed of a numerical value...
