Author Archives: Dhananjay Kumar

When to use viewProviders in Angular – Simplified

I have often seen developers are confused about viewProviders property of the @Componnet decorator.  This post explains to you about the viewProviders option. The viewProviders defines the set of injectable objects that are visible to its view, DOM children. They are not visible to the content children. At the component level, you can provide a service in two ways: Using the providers arrayUsing the viewProviders array. IfContinueContinue reading “When to use viewProviders in Angular – Simplified”

A JavaScript function inside a Block Scope: Simplified

Scoping determines the visibility of a variable, an object, or a function.  For example, a variable defined inside a function is visible or can be accessed only inside that particular function.   JavaScript has 4 types of scope.  Global scopeFunctional scopeLexical ScopeBlock Scope Out of the above four scoping, Block Scoping became part of JavaScriptContinueContinue reading “A JavaScript function inside a Block Scope: Simplified”

How to use useClass with Tree Shakable Services in Angular

Recently, I was asked that how can we use providers such as useClass inside a Tree Shakable service?   By default, Angular services are tree shakable, which means if the application does not use them, they are not part of the final bundle. So, if you create a service using CLI as, ng g s LogContinueContinue reading “How to use useClass with Tree Shakable Services in Angular”

How to manually pass the value of ‘this’ object in a JavaScript function

Every JavaScript function has a ‘this’ object, and the value of ‘this’ object depends on the way you call the function. To pass the value of ‘this’ manually, you need to call the function indirectly. In JavaScript, you call a function indirectly to pass the value of ‘this’ object manually. Manually calling a function isContinueContinue reading “How to manually pass the value of ‘this’ object in a JavaScript function”

Do Angular useExisting providers create a new object of service?

Short answer is NO, the useExisting provider use object created by other tokens. Read on, To learn more about such concepts, join a free webinar on Saturday, 20 June 4 PM IST. RSVP here: https://www.meetup.com/Geek97/events/271292371/ In Angular, providers determine how an object of a particular token gets created. That means whether Angular creates a newContinueContinue reading “Do Angular useExisting providers create a new object of service?”

How to make a property non-enumerable in JavaScript?

By default, all the properties of JavaScript objects are enumerable. That means you can enumerate them in a for loop or read them using the Object.values(). Let us consider an object Dog as shown below, let Dog = { name :’foo’, age: 9, canRun : true, eatMilk : false } You can enumerate all propertiesContinueContinue reading “How to make a property non-enumerable in JavaScript?”

How to merge arrays using spread operator in JavaScript?

Have you come across a requirement to merge two or more arrays  into another array? Let us say, you have two arrays as shown below, const metrocities = [‘Delhi’, ‘Mumbai’,’Chennai’,’Bangalore’,’Hyderabad’]; const smallcities = [‘Jamshedpur’,’Pune’,’Lucknow’,’Trivandrum’]; You need to merge them in another array with optional extra elements in the resultant array. JavaScript array spread operator makesContinueContinue reading “How to merge arrays using spread operator in JavaScript?”

How to create Private Properties in JavaScript.

We don’t have Access Modifiers in JavaScript, and all properties of an object are public, which means you can read and modify them outside the object. But what if you have a requirement to create private properties?  Consider Product object as mentioned below, let Product = { id: ‘1’, price: 200, title: ‘Pencil’ } console.log(Product.id);ContinueContinue reading “How to create Private Properties in JavaScript.”