Javascript Articles - Page 387 of 534

In this artcle we are going to learn another method other than a constructor in a JavaScript class with suitable examples in JavaScript The Constructor is used to create and initialize an instance of a class i.e., object. The constructor's job is to build a new object and set values for any attributes that already exist on the object. Every class has a default constructor. If we don’t provide our own constructor, then the default constructor will be incoked. Let’s understand this concept in a better way with the help of suitable examples further in this article. Syntax The syntax ... Read More

"this" keyword in an arrow functionThe JavaScript 'this' keyword refers to the object it belongs to. In an arrow function, 'this' belongs to a global object. Inside a simple function, there might be chances that 'this' keyword can result in undefined but in an arrow function it results in an exact value.ExampleLive Demo    function Student(fname, grade) {       this.fname = fname;       this.grade = grade;       this.details = function() {          return () => {             document.write(`Hi, I'm ${this.fname} from ${this.grade} grade`);          };       }    } let info = new Student('picaso', 'seventh'); let printInfo = info.details(); printInfo(); OutputHi, I'm picaso from seventh grade

In this article we are going to discuss how to convert JavaScript objects to primitive data types manually with suitables examples in JavaScript. Primitive data types are nothing but a string, number, boolean, etc. To convert objects to primitive data types, javascript has provided some methods such as toString(), toDateString(), valueOf(), etc. Using these methods javascript objects can be easily converted to primitive data types. Using the toString() method This method returns a string value representing the string format of the given object. The syntax to convert a javascript object into a primitive date type (string, in this example) is ... Read More

In this article we are going to discuss how to convert a JSON string into a JavaScript object with suitables examples in JavaScript. There are two possible ways to convert a JSON string into a Javascript object – eval() and parse(). The usage of eval() method is unsafe and not preferred. It is vulnerabable to hackers. The parse() method is preferred in general anytime. The typical application for JSON is Data transfer to and from a web server. The data that has been sent from a server is always a JSON string. Using JSON.parse(), we can convert the JSON string ... Read More

In this article we are going to discuss how to convert a value to a number in JavaScript. JavaScript has introduced Number(), parseInt(), parseFloat() methods to convert a value into a number and also we can achieve it by using (+) unary operator. These mentioned methods can convert number strings to numbers and Boolean values to 1's or 0's. Let’s us discuss these above mentioned methods briefly. We’ll discuss the 4 possible ways to convert a value to a number with an example each. Number() parseInt() parseFloat() Unary Opertaor(+) Example 1 The following is an example program to ... Read More

In the following example we are going to learn how to set dynamic property keys to an object in JavaScript. To add dynamic property keys to an object in JavaScript, there are three possible ways. There are three possible ways to set dynamic property keys to an object. The first possible way is to create a key and assign it to the object, second possible way is to set the dynamic property keys to an object using the define property method and the third possible way is to set the dynamic property keys to an object using ES6 method. We ... Read More

In this article we are going to discuss how to access an object value using variable key in JavaScript. An object value can be accessed by a Dot Notation and a Bracket Notation. To get the object value through a variable key, the value or expression inside the bracket notation must match with the existing key name, then it returns a value. The bracket notation, unlike the dot notation can be used with variables. If we are using a variable with bracket notation, the variable must reference a string. Let’s understand this concept better with the help of examples further ... Read More

The ()(parenthesis) brackets play an important role in accessing a function. Accessing a function without () will return the function definition instead of the function result. If the function is accessed with () then the result can be obtained.Without ()ExampleIn the following example, the function is accessed without () so the function definition is returned instead of the result as shown in the output.Live Demo function toCelsius(f) { return (5/9) * (f-32); } document.write(toCelsius); Outputfunction toCelsius(f) { return (5/9) * (f-32); ... Read More

In this article we are going to learn how to find the action attribute and method of a form with suitable examples in JavaScript. In HTML, there is  elements which has few attributes: input, label, text area, select, name, target. The action and method attributes of the form are used to return those values. The action attribute also specifies where to send the form data when form is submitted. To get a better idea of this concept, let’s look into JavaScript examples where we achieved the given task using action attribute and also with method attribute. Using action ... Read More

In this article we are going to discuss how to display the date and time of a document when it is last modified in JavaScript. It is important to know the last updated date and time of a web document, when you read some content on the web, to know whether the web document is latest or outdated. The Document object has lastModified property which returns us the last modified date and time of a document. This is a read-only property. The value of the lastModified property is obtained by the HTTP header from the web server. For people who ... Read More