The difference between Call, Apply and Bind can be explained with below examples, Call: The call() method invokes a function with a given this value and arguments provided one by one, Apply: Invokes the function and allows you to pass in arguments as an array, bind: returns a new function, allowing you to pass in an array and any number of arguments. The debugger statement invokes any available debugging functionality, such as setting a breakpoint. Resizing the browser window, changing the font, content changing (such as user typing text), using JavaScript methods involving computed styles, adding or removing elements from the DOM, and changing an element's classes are a few of the things that can trigger reflow. // returns [1, 2]; original array: [3, 4, 5], // returns [4, 5]; original array: [1, 2, 3], //returns [4]; original array: [1, 2, 3, "a", "b", "c", 5], //false, refer different objects in memory, // Add 10 to the given argument and display the value, // returns a function: b => c => 1 + b + c, // 30 (because if block variable won't exist here), //10000 (accessible to due function scope), //error: age is not defined(due to block scope). Object literals make it easy to quickly create objects with properties inside the curly braces. Post message is a method that enables cross-origin communication between Window objects. Let's map city names from Countries array. The syntax would be as below. Hence, the prototype for 'trimLeft' is always 'trimStart'. To manipulate an ArrayBuffer, we need to use a “view” object. The questions provided in this repository are the summary of frequently asked questions across numerous companies. The unary(+) operator is used to convert a variable to a number.If the variable cannot be converted, it will still become a number but with the value NaN. Scope is the accessibility of variables, functions, and objects in some particular part of your code during runtime. Below are the main applications of Object.seal() method. Browsers provide an XMLHttpRequest object which can be used to make asynchronous HTTP requests from JavaScript by passing the 3rd parameter as true. We can then use these labels to refer back to the code later. For example, name and age properties defined insider constructor as below. Otherwise you will receive an error Error: Cannot read property 'length' of undefined as mentioned above. Native objects are objects that are part of the JavaScript language defined by the ECMAScript specification. The strict operators take type of variable in consideration, while non-strict operators make type correction/conversion based upon values of variables. Since JSON is text only, it can easily be sent to and from a server, and used as a data format by any programming language. Two numbers are strictly equal when they are numerically equal. It isn't necessarily restricted to a web application. JavaScript is the official language of all modern web browsers.As such, JavaScript questions come up in all sorts of developer interviews. I was asked recently by a friend of mine to come up with a list of interview questions that you can get asked during a Javascript interview. Yes, it is possible to get and debug HTML elements in the console just like inspecting elements. Let's take an example for both arrays and object use cases. Let's take an example of global modifier. Table of Contents. There are 5 types of primitive data types. If declared at the beginning of a script, it has global scope. Note: It allows Node.js to perform non-blocking I/O operations even though JavaScript is single-threaded. Intermediate Level JavaScript Interview Questions Q22. If you still try to access, it throws a run-time ReferenceError(i.e, inner is not defined). You can use the Object.keys() method which is used to return an array of a given object's own property names, in the same order as we get with a normal loop. For example, let's pass the same signal to multiple fetch calls will cancel all requests with that signal, When a new javascript program is executed directly from console or running by the, When an event fires, the event callback added to task queue, When a setTimeout or setInterval is reached, the corresponding callback added to task queue, Polyfill features that are missing in your target environment (using @babel/polyfill), Source code transformations (or codemods). Whereas if the opening curly brace is along with the return keyword then the function is going to be returned as expected. You can use the