Americas
Europe
Delve into the world of computer science with an engaging insight into Javascript syntax. This comprehensive guide will walk you through all the essential elements, from basics to advanced concepts. You'll uncover the essentials of object syntax, get to grips with class syntax, and gain a deep understanding of function syntax. Moreover, explore the striking contrasts between Java and Javascript syntax, and learn from practical examples. Whether you're a novice seeking a starter guide or an experienced programmer aiming to deepen your knowledge, this insightful content offers a complete lowdown on the crucial Javascript syntax.
Explore our app and discover over 50 million learning materials for free.
Lerne mit deinen Freunden und bleibe auf dem richtigen Kurs mit deinen persönlichen Lernstatistiken
Jetzt kostenlos anmeldenDelve into the world of computer science with an engaging insight into Javascript syntax. This comprehensive guide will walk you through all the essential elements, from basics to advanced concepts. You'll uncover the essentials of object syntax, get to grips with class syntax, and gain a deep understanding of function syntax. Moreover, explore the striking contrasts between Java and Javascript syntax, and learn from practical examples. Whether you're a novice seeking a starter guide or an experienced programmer aiming to deepen your knowledge, this insightful content offers a complete lowdown on the crucial Javascript syntax.
Javascript Syntax is the set of rules that define how Javascript programs can be constructed. Syntax in programming is similar to grammar in spoken and written languages, where the specific arrangement of symbols conveys a specific meaning. Understanding the syntax of Javascript paves the way for mastering this versatile programming language.
Javascript syntax includes various constructs such as variables, data types, expressions, loops and conditionals, and functions. In this journey into the Javascript syntax, you will delve deep into these crucial components.
Variables: In Javascript, variables are containers used to store data values. They can be created using 'var', 'let', or 'const' keywords followed by an identifier(name). The assignment operator = is used to assign a value to a variable.
let name = "JavaScript"; const PI = 3.14;
Data Types: Javascript has several data types including Number, String, Boolean, Object, Null and Undefined.
Expressions: Javascript expression is a piece of code that resolves to a value. It can be a literal value, variables, or operators that compute a value.
let total = 10 + 5; // 15 let result = total > 5; // true
Explanations 
Exams 
Magazine 
let student = {
firstName: "John",
lastName: "Doe",
age: 20,
grade: "Sophomore"
}
class Rectangle {
constructor(height, width) {
this.height = height;
this.width = width;
}
}
function greet() {
return "Hello, world!";
}
An example of a Javascript function that takes two parameters and returns their sum:
function sum(a, b) {
return a + b;
}
While Javascript and Java share part of their names, they are important differences in their syntax and structure. Each has unique features that make it suitable for different types of projects. These are separate languages with their distinct rules for defining variables, writing functions and controlling the program flow.
| Javascript | Ideal for web development, as it integrates seamlessly with HTML and CSS. With Javascript, you can create interactive web pages, handle events, build games, and even develop full-fledged web applications thanks to libraries and frameworks like Node.js, Angular and React. |
| Java | Java is a statically typed, compiled language that excels in building server-side applications, video games and mobile apps. It is extensively used in enterprise-scale applications, Android development, and in systems that require robustness and reliability. |
The syntax differences between Javascript and Java can sometimes lead to confusion, especially for beginners. The differences are quite stark.
// Javascript dynamically-typed variable let message = 'Hello World'; message = 100; // This is perfectly fine // Java statically-typed variable String message = "Hello World"; message = 100; // This will cause a compile error
Here is an example of defining a class in both languages:
// Javascript
class Student {
constructor(name, grade) {
this.name = name;
this.grade = grade;
}
}
// Java
public class Student {
private String name;
private String grade;
public Student(String name, String grade) {
this.name = name;
this.grade = grade;
}
// We would also add getter and setter methods in Java
}
Your choice between Javascript or Java should not be based merely on the complexity of syntax. It's essential to consider factors like runtime environments, use cases, performance considerations, community support, and availability of learning resources. Both languages continue to evolve and remain prominent in the ever-changing landscape of programming.
Diving into practical examples is a terrific way to grasp the fundamentals of Javascript syntax. These examples serve as a stepping stone towards understanding how to use variables, functions, classes, and objects effectively in Javascript.
An excellent place to start when unravelling Javascript syntax is by exploring a variety of practical examples. You will notice that Javascript syntax establishes clear rules on how your Javascript programs should be structured. Each construct like variables, classes, functions, and objects has a specific syntax that you need to adhere to.
Let's explore some substantive examples. First, we'll look at the syntax for declaring and using variables in Javascript. Variables serve as placeholders for different types of data that you’re working with in your program.
let studentName = "John Doe"; let studentAge = 20; let studentGrade = "Sophomore";
In these examples, `let` is used to declare a variable. `studentName`, `studentAge`, and `studentGrade` are the names of the variables, and the `=` is the assignment operator, which assigns the values `"John Doe"`, `20`, and `"Sophomore"` to the respective variables.
Next, we'll take a look at how to use conditional statements in Javascript. Conditional statements allow your code to make decisions based on certain conditions.
let grade = 85;
if (grade >= 70) {
console.log("Passed");
} else {
console.log("Failed");
}
In the above example, we have an `if-else` conditional statement. If the condition in the parentheses (`grade >= 70`) is met, the code within the `{}` after the `if` statement is executed. If not, the code in the `{}` after the `else` statement is run.
A function is a block of organised, reusable code that is used to perform a single, related action. Javascript functions provide the ability to create custom code segments that can be called whenever necessary. In Javascript, functions can be treated like any other type, so they can be stored in a variable, array or passed as an argument to other functions.
pre> function square(num) { return num * num; } let result = square(10); // result is 100The `function` keyword is used to initiate the definition of a function. In the example, `square` is the function's name, and `num` in the parentheses is known as the function parameter. Inside the function block (within the `{}` brackets), the code is defined that needs to be executed whenever that function is called. The `return` keyword is then used to specify the result that the function should yield, in this case, the square of the number.
Javascript classes introduced in ECMAScript 2015 are primarily syntactical sugar over Javascript's existing prototype-based inheritance. Classes are in fact "special functions". Just as you can define function expressions and function declarations, the class syntax has two components: class expressions and class declarations.
class Rectangle {
constructor(height, width) {
this.height = height;
this.width = width;
}
area() {
return this.height * this.width;
}
}
let myRectangle = new Rectangle(5, 10);
console.log(myRectangle.area()); // Output: 50
Here, `Rectangle` is a class that includes a `constructor` method for initialising object instances of the class. The `area` method is another method of the class that calculates the area of the rectangle. A new instance of `Rectangle` is then created using the `new` keyword `let myRectangle = new Rectangle(5, 10);`, and the `area` method is then called on this object using the dot notation `myRectangle.area()`.
let student = {
name: 'John Doe',
age: 20,
grade: 'Sophomore',
study: function() {
console.log(this.name + ' is studying');
}
}
console.log(student.name); // Output: John Doe
student.study(); // Output: John Doe is studying
In the example of a `student` object, `name`, `age` and `grade` are properties, while `study` is a method. The `this` keyword is used within the method to refer to the current object. When accessing an object's properties or methods, we use the dot notation, for example, `student.name` and `student.study()`. The `student.study()` allows us to invoke or call the function.
Getting to grips with the fundamentals of Javascript syntax is an imperative step in your journey towards mastering this popular and powerful programming language. Javascript plays a pivotal role in modern web development, aiding in creating interactive and dynamic web pages. This comprehensive guide will walk you through key aspects of the language's syntax, shedding light on functions, classes, and objects in Javascript.
Learning Javascript syntax lays the groundwork for your understanding of not just Javascript but also programming in general. It’s like learning the basic vocabulary before you start writing essays. In Javascript, some of the most common syntax elements you'll come across are variables, operators, data types, functions, loops, and conditions.
var, let, or const keyword.let x; // x is undefined x = 5; // x is a number x = "John"; // x is a string
Given their importance, understanding Javascript function syntax is fundamental for any novice programmer. A Javascript function is a block of code that performs a specific task. It is a set of statements that performs a task or calculates a value. To use a function, you must define it somewhere in the scope from which you wish to call it.
The general form of a function definition in Javascript is:
function functionName(parameters) {
// code to be executed
}
Here, the `function` keyword indicates that you're defining a function. The `functionName` refers to the name you assign to the function (note: it’s a best practice to start the function name with a verb as a function usually execute an action). The `parameters` are inputs to the function (you can have multiple parameters separated by commas). The `{}` contains the code to be executed - this is known as the function body.
Once a function has been defined, it can be used by calling it from another function or directly from the Javascript code. For example:
function sayHello(name) {
return "Hello, " + name;
}
console.log(sayHello("John")); // prints: Hello, John
Javascript classes are a recent addition, released with ECMAScript 2015 or ES6. Classes are essentially syntactic sugar over Javascript's existing prototype-based inheritance mechanism. They provide a much cleaner and convenient syntax to create objects and deal with inheritance.
Here is a basic definition of a class in Javascript:
class MyClass {
constructor() { ... }
method1() { ... }
method2() { ... }
}
The `class` keyword indicates the beginning of a class declaration. `MyClass` is the name of the class and by convention, it is written in CamelCase. The `constructor` method is a special method for creating and initializing an object. `method1` and `method2` are two methods that can be defined inside the class. Methods in a class don't require a `function` keyword.
A class can be used in code as follows:
let myInstance = new MyClass();
In Javascript, objects are key-value pairs. The keys in this pair are known as properties and they reference values that can be of any type, including other objects or functions.
The most straightforward way to create an object in Javascript is to use object literals:
let student = {
name: 'John Doe',
age: 20
};
In this example, `student` is an object variable. Inside the `{}`, properties are defined in a `key: value` fashion, separated by commas. Each property can be accessed using the dot notation `student.name` or bracket notation `student['name']`.
Objects are mutable and properties can be added or removed from them after their creation. A method is a function that is associated with an object:
let student = {
name: 'John Doe',
age: 20,
greet: function() { return 'Hello ' + this.name; }
};
Here, `greet` is a method linked with the `student` object. This method can be called as `student.greet()`.
Extending your knowledge of Javascript syntax further, we'll navigate the sometimes tricky terrains of advanced concepts. You’ll encounter a deeper understanding of functions, delve into classes and objects in Javascript, advancing your skills as a Javascript programmer.
Taking a closer look at Javascript syntax, several complex concepts come into play. Beyond the fundamentals of variables, operators, loops, and conditional statements, a plethora of advanced concepts deserves your attention. These include closure, callback functions, promises, async/await, destructuring and template literals, among others.
A fundamental aspect of Javascript syntax is the use of functions. Functions are of great importance and form the basis of modular programming in Javascript. An understanding of the different types of functions, from arrow functions to generator functions, is crucial.
An Arrow Function:
Arrow functions provide a concise syntax to write functions in Javascript. Unlike regular functions, arrow functions do not bind their own "this" value. Thus, the "this" inside an arrow function is the same as the "this" outside the function. An arrow function expression syntax is as follows:
const myFunction = (parameter1, parameter2) => {
// code to be performed
}
A Generator Function:
Generator functions are a special kind of function that return a Generator object. Generators are functions that can be exited and later re-entered, with their context (variable bindings) remembered across re-entrances.
function* name(parameters) {
// code to be performed
}
Javascript Class syntax is more advanced than our earlier consideration. A Javascript class allows you to create an object-oriented design in Javascript. Besides the basic structure of a class, methods, class expressions, subclasses and superclasses are key concepts of a Javascript class.
Getter and Setter Methods:
Classes in Javascript can include getter and setter methods. Getters are methods that get and return the internal properties of an object. However, setters are methods that modify the values of the object’s properties.
class MyClass {
constructor() { ... }
get myProperty() {
return this.property
}
set myProperty(value) {
this.property = value;
}
}
Subclasses and Superclasses:
In Javascript, classes can inherit from other classes in a hierarchical structure. Here, the class that is inherited from is often referred to as a superclass and the class that does the inheriting is the subclass.
class Rectangle {
constructor(height, width) {
this.height = height;
this.width = width;
}
}
class Square extends Rectangle {
constructor(sideLength) {
super(sideLength, sideLength);
}
}
Javascript objects are certainly more advanced than they first appear. Beyond basic object definitions and methods, understanding getters and setters, object constructors, prototypes, and object-oriented design patterns is central to mastering advanced Javascript syntax.
Object Constructor:
An object constructor is a special method used to initialize a newly created object. In Javascript, constructors have the same name as the class and they are invoked when an object is created.
function Person(first, last, age, eye) {
this.firstName = first;
this.lastName = last;
this.age = age;
this.eyeColor = eye;
}
Prototypes:
Javascript objects inherit properties and methods from a prototype. The Object.prototype is on the top of the prototype chain. All Javascript objects (Date, Array, RegExp, Function, ....) inherit from the Object.prototype.
YOUR SCORE
Your score:
Already have an account? Log in
SIGNUP SIGNUPFlashcards in Javascript Syntax15
Start learningWhat is Javascript Syntax?
Javascript Syntax is the set of rules that define how Javascript programs can be constructed, similar to grammar in spoken and written languages.
What are the basics of Javascript Syntax?
Javascript syntax includes constructs such as variables, data types, expressions, loops and conditionals, and functions.
What is the syntax for creating a class in Javascript?
A Javascript class definition starts with the keyword 'class' followed by the class name and it's called syntactical sugar over Javascript's existing prototype-based inheritance.
What are the use cases for Javascript and Java respectively?
Javascript is ideal for web development, creating interactive web pages, handling events, building games and web applications. Java is a statically typed, compiled language used in building server-side applications, video games, mobile apps and in enterprise-scale applications.
What are the key differences between the syntax of Javascript and Java?
Javascript is dynamically-typed and prototype-based, with functions as first-class objects. Java is statically-typed and class-based, without the flexibility to manipulate methods the way Javascript does.
Based on syntax complexity, which language would be considered more complex, Java or Javascript?
Java syntax is considered more complex than Javascript syntax.
Already have an account? Log in
Open in AppHow would you like to learn this content?
How would you like to learn this content?
Free computer-science cheat sheet!
Everything you need to know on . A perfect summary so you can easily remember everything.
The first learning app that truly has everything you need to ace your exams in one place
Sign up to highlight and take notes. It’s 100% free.
Save explanations to your personalised space and access them anytime, anywhere!
Sign up with Email Sign up with AppleBy signing up, you agree to the Terms and Conditions and the Privacy Policy of StudySmarter.
Already have an account? Log in
