Knockout Js Interview Questions And Answers Pdf

knockout js interview questions and answers pdf

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Introduction KnockoutJS is being used more frequently in projects as a lightweight tool to assist quick development in the browser, especially where ViewModels and arrays are involved. Knockout is quick to learn and while it doesnt have anywhere near the functionality of say AngularJS, it does provide a powerful mechanism for working with data and vastly reduces the amount of code needed to implement a robust modern, client-side solution. Unlike Angular, which encompasses many concepts including data-binding, integrated testing, view management, etc.

Knockout Js Interview Questions

Work fast with our official CLI. Learn more. If nothing happens, download GitHub Desktop and try again. If nothing happens, download Xcode and try again. If nothing happens, download the GitHub extension for Visual Studio and try again. Pull Requests are highly appreciated. Follow me SudheerJonna for technical updates. You can download the PDF and Epub version of this repository from the latest run on the actions tab.

The questions provided in this repository are the summary of frequently asked questions across numerous companies. We cannot guarantee that these questions will actually be asked during your interview process, nor should you focus on memorizing all of them. The simplest way to create an empty object is using the Object constructor. Currently this approach is not recommended. This is equivalent to an instance created with an object create method with a function prototype and then call that function with an instance and parameters as arguments.

A Singleton is an object which can only be instantiated one time. Repeated calls to its constructor return the same instance and this way one can ensure that they don't accidentally create multiple instances. Prototype chaining is used to build new types of objects based on existing ones. It is similar to inheritance in a class based language.

The prototype on object instance is available through Object. Call: The call method invokes a function with a given this value and arguments provided one by one.

Call and apply are pretty interchangeable. Both execute the current function immediately. You can remember by treating Call is for comma separated list and Apply is for Array. Whereas Bind creates a new function that will have this set to the first parameter passed to bind. It is useful when you want to transmit data across a network and it is basically just a text file with an extension of.

The slice method returns the selected elements in an array as a new array object. It selects the elements starting at the given start argument, and ends at the given optional end argument without including the last element. If you omit the second argument then it selects till the end. Some of the examples of this method are,. Note: Slice method won't mutate the original array but it returns the subset as a new array.

The first argument specifies the array position for insertion or deletion whereas the option second argument indicates the number of elements to be deleted. Each additional argument is added to the array. Objects are similar to Maps in that both let you set keys to values, retrieve those values, delete keys, and detect whether something is stored at a key. Due to this reason, Objects have been used as Maps historically. But there are important differences that make using a Map preferable in certain cases.

The strict operators follow the below conditions for different types,. An arrow function is a shorter syntax for a function expression and does not have its own this, arguments, super, or new. These functions are best suited for non-method functions, and they cannot be used as constructors.

In Javascript, functions are first class objects. First-class functions means when functions in that language are treated like any other variable. For example, in such a language, a function can be passed as an argument to other functions, can be returned by another function and can be assigned as a value to a variable. For example, in the below example, handler functions assigned to a listener.

Higher-order function is a function that accepts another function as an argument or returns a function as a return value. Unary function i. Let us take an example of unary function. It stands for a single argument accepted by a function. Currying is the process of taking a function with multiple arguments and turning it into a sequence of functions each with only a single argument.

Currying is named after a mathematician Haskell Curry. By applying currying, a n-ary function turns it into a unary function. Let's take an example of n-ary function and how it turns into a currying function. A Pure function is a function where the return value is only determined by its arguments without any side effects. Let's take an example to see the difference between pure and impure functions,. As per above code snippets, Push function is impure itself by altering the array and returning an push number index which is independent of parameter value.

Whereas Concat on the other hand takes the array and concatenates it with the other array producing a whole new array without side effects. Also, the return value is a concatenation of the previous array. Remember that Pure functions are important as they simplify unit testing without any side effects and no need for dependency injection. They also avoid tight coupling and make it harder to break your application by not having any side effects.

These principles are coming together with Immutability concept of ES6 by giving preference to const over let usage. The let statement declares a block scope local variable. Hence the variables defined with let keyword are limited in scope to the block, statement, or expression on which it is used. Whereas variables declared with the var keyword used to define a variable globally, or locally to an entire function regardless of block scope.

Let's take an example to demonstrate the usage,. Let is a mathematical statement that was adopted by early programming languages like Scheme and Basic. It has been borrowed from dozens of other languages that use let already as a traditional keyword as close to var as possible.

If you try to redeclare variables in a switch block then it will cause errors because there is only one block. For example, the below code block throws a syntax error as below,. To avoid this error, you can create a nested block inside a case clause and create a new block scoped lexical environment. The Temporal Dead Zone is a behavior in JavaScript that occurs when declaring a variable with the let and const keywords, but not with var.

Let's see this behavior with an example,. The signature of it would be as below,. Each time a memoized function is called, its parameters are used to index the cache. If the data is present, then it can be returned, without executing the entire function. Otherwise the function is executed and then the result is added to the cache.

Let's take an example of adding function with memoization,. Hoisting is a JavaScript mechanism where variables and function declarations are moved to the top of their scope before code execution. Remember that JavaScript only hoists declarations, not initialisation. Let's take a simple example of variable hoisting,. For example, the prototype based inheritance written in function expression as below,.

A closure is the combination of a function and the lexical environment within which that function was declared. The closure has three scope chains.

As per the above code, the inner function greetingInfo has access to the variables in the outer function scope Welcome even after the outer function has returned. Modules refer to small units of independent, reusable code and also act as the foundation of many JavaScript design patterns.

Most of the JavaScript modules export an object literal, a function, or a constructor. Scope is the accessibility of variables, functions, and objects in some particular part of your code during runtime. In other words, scope determines the visibility of variables and other resources in areas of your code.

A Service worker is basically a script JavaScript file that runs in the background, separate from a web page and provides features that don't need a web page or user interaction. Some of the major features of service workers are Rich offline experiences offline first web application development , periodic background syncs, push notifications, intercept and handle network requests and programmatically managing a cache of responses.

Service worker can't access the DOM directly. But it can communicate with the pages it controls by responding to messages sent via the postMessage interface, and those pages can manipulate the DOM. The problem with service worker is that it gets terminated when not in use, and restarted when it's next needed, so you cannot rely on global state within a service worker's onfetch and onmessage handlers.

This API uses indexes to enable high-performance searches of this data. The web storage provides two mechanisms for storing data on the client. Post message is a method that enables cross-origin communication between Window objects.

Generally, scripts on different pages are allowed to access each other if and only if the pages follow same-origin policy i. A cookie is a piece of data that is stored on your computer to be accessed by your browser. For example, you can create a cookie named username as below,. Cookies are used to remember information about the user profile such as username.

It basically involves two steps,. You can delete a cookie by setting the expiry date as a passed date. You don't need to specify a cookie value in this case.

300+ TOP KnockoutJS Interview Questions and Answers

Observable is a property of knockoutJS that contain the view model. This property is bind with UI View in two-way binding. The Observable cluster is KnockoutJs properties that contain the thing gathering in the view model and this property is tie with UI View in two way binding. Need event to call data model and update it. Model part is not directly bind with the view page. Models directly bind with the view-model and view-model directly with the view page. Model parts directly bind with the view page.

Work fast with our official CLI. Learn more. If nothing happens, download GitHub Desktop and try again. If nothing happens, download Xcode and try again. If nothing happens, download the GitHub extension for Visual Studio and try again.


Read Top knockout js interview questions. Download Knockout js Interview Questions PDF. Below are the list of Best Knockout js Interview Questions and Answers.


KnockoutJS Interview Questions

JavaScript Interview Questions Javascript is one of most popular programming language for the web. It is widely used for creating interactive client-side web applications and games. Javascript can be also used as server-side programming language. It is dynamic, weakly typed, prototype-based and multi-paradigm high-level programming language.

Anil Singh is an author, tech blogger, and software programmer. Book writing, tech blogging is something do extra and Anil love doing it. For more detail, kindly refer to this link..

Knockout provides a simple two-way binding mechanism to link a data model to an UI and update takes place. Thus making synchronization between them a breeze. Aarush is a web developer from Surat, Gujarat. He worked internationally, in-house, and remotely on projects for leading brands, agencies, startups, and charities. Create your online presense.

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Ans: KnockoutJS is a JavaScript library that helps developers create modern, rich user interfaces with a clean underlying data model. Whenever you have a user-interface that needs to update when an underlying data model updates, then KnockoutJS is a useful tool that could be used. It is an open source project, and is used to power the front-end of the beautifully designed Azure control interface. Ans: The Computed observable is a KnockoutJs function which is depends on the other observable properties.

KnockoutJS is a JavaScript library that helps developers create modern, rich user interfaces with a clean underlying data model. Whenever you have a user-interface that needs to update when an underlying data model updates, then KnockoutJS is a useful tool that could be used. It is an open source project, and is used to power the front-end of the beautifully designed Azure control interface.

What is KnockoutJS? It is a JavaScript library which is based on MVVM pattern that helps developers in building rich and responsive websites. Who is the author of KnockoutJS? Steve Sanderson is the author of KnockoutJS. What are the different ways of using templates in KnockoutJS? Different ways of using templates in KnockoutJS are:.

KnockoutJS is being used more frequently in projects as a lightweight tool to assist quick development in the browser, especially where ViewModels and arrays are involved. Unlike Angular, which encompasses many concepts including data-binding, integrated testing, view management, etc. Due to its increasing popularity, questions about it are being asked at interviews — this is a list of some of the more common questions I have seen discussed in preparing interviews. If you understand these concepts, you will be well on your way to putting together a solid Knockout solution. For simple working examples of Knockout, you can download examples from some of my other articles listed below:.

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