Category: JavaScript
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Explain Object.keys in JavaScript
Enumerating through the properties of a JavaScript object is a persistent requirement. Hence it becomes a popular question in a JavaScript interview. Any good JavaScript developer must know about various available options. Note: You can find a video tutorial on the same at the end of the article. To start with considering the Dog object […]
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Five Things about JavaScript delete operator
A better understanding of delete operator is necessary for JavaScript developers. As the name suggests, the delete operator deletes properties from the object. You can delete a property as shown below: It returns true on successful deletion. However, in some cases, it may return true even if it does not delete a property. In this […]
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All about NaN in JavaScript
In JavaScript, NaN is one of the most confusing concepts; hence, it is often asked in the interview. You may have come across questions such as, What is NaN What is the type of NaN How to check for the NaN What is the difference between isNaN() and Number.isNaN() In this post, let us learn […]
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Simplifying Maps in the JavaScript
Maps is a data structure, which stores the key/value pair in an ordered way. Since the inception of the JavaScript, objects are primarily used for the map. Consider the below code listing: To store two key/value pairs, we have created an object foo and using the keys such as id and color to retrieve […]
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Why you need Proxy objects in JavaScript
JavaScript is not truly Object Oriented language, hence implementing requirements as stated below could be challenging. For example, Throw an error if the setting value of a property does not satisfy a particular condition If the property does not exist on set some default value instead of undefined If the property does not exist on […]
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Step by Step implementing Two-Way Data Binding in Vanilla JavaScript
Data Binding is one of the most important features of all the frameworks. It ensures that the data model and the views are in sync with each other. It is very fundamental feature of any MV* frameworks such that Model-View-Controller, Mode-View-ViewModel, and Model-View-Presenter, etc. Popular JavaScript based frameworks such that React, Angular have their way […]
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Type of Undeclared Variable in JavaScript: What is it?
Have you ever thought, what is type of undeclared variable in JavaScript? I know, the first thing that might come to mind is: how can an undeclared variable have a type? Yes, in JavaScript it is possible. To understand it, let us start with understanding types in JavaScript. There are seven built in types in JavaScript. […]
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Simplifying Object.assign method in JavaScript
Read full article on the Infragistics blog “In JavaScript, Object’s assign method copies source object’s own enumerable properties to a target object, and returns that target object “ There are two important keywords in the above sentence: Enumerable Own Before we go ahead and understand purpose of Object.assign, it is essential that we really understand these two words, […]
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Two Problems of a JavaScript Class
Starting ECMA 6, JavaScript has class keyword to create a class. I have written in detail about class here. There is no second question that class simplifies the way object is created, inheritance is implemented etc. JavaScript class has, Constructors Methods Extends etc. Above features of a class helps to easily write Object Oriented […]
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How to add a static member property in a JavaScript class?
Recently while solving a problem, I came across a requirement to create a property in a JavaScript class, which needs to be shared by all the object instances. In the programming world, these types of properties are called Static Properties. There are various scenarios when you need a static member property: When counting number of […]
Dhananjay Kumar 