Javascript Data Types
JavaScript data types include primitive types such as numbers, strings, booleans, null, and undefined, as well as complex types like objects and functions. These data types determine the kind of data that can be stored and manipulated in JavaScript programs. Understanding data types is essential for effectively working with variables and performing operations in JavaScript.
3 Key excerpts on "Javascript Data Types"
eBook - ePubConfident Web Design
Master the Fundamentals of Website Creation and Supercharge Your Career
- Kenny Wood(Author)
- 2018(Publication Date)
- Kogan Page(Publisher)
...Objects are so important in JavaScript, so take the time to make sure that you understand them until the point where looking at the syntax feels like second nature. I encourage you to go off and create some other objects. Why not create one for a car or for a musical instrument? Start thinking in a more programmatically minded way about how to transpose real-life objects into a JavaScript object. Getting into the mindset of a programmer is so important on the journey to understanding JavaScript and becoming a fantastic web developer. You’re doing great – keep it up! var x = “Hello”; // Assigning a string var y = 12; // Assigning a number Data types play a very important part in programming and understanding them is a fundamental part of your learning of JavaScript and its concepts. JavaScript handles the assigning of data types for you when you declare your variables. It will detect the data type you have assigned, based on your syntax. You do not have to specifically state which type of data your variable holds, like you might do in a different programming language. It’s important to understand both the benefits and limitations of each data type, to help you to understand what you can do with each. So let’s first understand just why data types are so important. Consider the following snippet of code: var x = “Hello”; // Assigning a string var y = 12; // Assigning a number var i = x + y; console.log(i); Now pause for a second and think about this snippet of code. What do you think will happen when we try to run this code? Will it break the code and produce an error message? Or will it try to output something in the console and fail there? Give it a go and see what happens for yourself. If you did go ahead and run the above code in your console to see what would happen, you were probably surprised by the result...
- 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)
...16 Perform Useful Operations This chapter describes the JavaScript operators and demonstrates how they can be used in your scripts. Convert Values Do Arithmetic Assign Values Make Comparisons Assess Logic Examine Conditions Juggle Bits Force Order Summary Convert Values Before performing operations in JavaScript it is important to recognize the data types of the values you are working with in order to avoid unexpected results. For example, the value 42 is a number, but the value ‘42’ is a string, so attempting to perform an addition with ‘42’ + 8 will return a string result of ‘428’, not the number 50. Happily, JavaScript provides a number of ways to return versions of values in other data types – without changing the value’s original data type. Strings to Numbers The JavaScript parseInt() built-in function can return an integer whole number version, in the number data type, of a string specified within its parentheses. For example, parseInt(‘42’) will return the number 42, so 42 + 8 will return a number result of 50. Similarly, the JavaScript parseFloat() built-in function can return a floating-point number version, in the number data type, of a string specified within its parentheses. Both these methods allow alphabetic characters to follow the numeric part of the specified string and strip them from the result – for example, parseInt(‘42nd Street’) returns number 42. If either of these functions cannot find a numeric value at the beginning of the specified string, the result will be NaN – a JavaScript property meaning “Not a Number”. You can also check if a value is not a number by specifying the value within the parentheses of a JavaScript isNaN() built-in function. This, too, will first attempt to find a number at the beginning of the specified value and return false if it finds a number (even from a specified string), otherwise it will return true if it cannot find a number. Conversion of data types is known as “coercion”, and it can be explicit or implicit...
