The general syntax of using the for-in loop is: Answer: Both .call() and .apply() functions are almost identical in their use, with a major exception in how arguments are passed to the function. Here are the three main ways to do so: Properties of screen objects are: Answer: The escape() function allows for converting a string into a coded form in JavaScript. ... Question: Write the code to force a page to load another page in JavaScript. Here is an excellent book with top Javascript programming questions and answers: JavaScript Interview Preparation: Practice Problems [Video]. Almost 70% of all the Stackoverflow survey respondents state that they have been using JS for their day-to-day development chores. Syntax Error – When the incorrect syntax is used, we get this error. Now let’s move on to the next section of JavaScript interview questions. Question: Could you tell us about the various types of error constructors supported by JavaScript? Answer: A cookie is simply data, usually small, sent from a website and stored on the user’s computer by the web browser used to access the website. These were originally designed for controlling fax machines, teletypes, and typewriters. Question: How will you empty an array in JavaScript? For example, you can assign functions to variables, to array elements, and to other objects. They are similar to properties but not as capable. For breaking the string into key and value, you can use the split() method. Unlike a property, an attribute is of the string data type. Question: Please explain NEGATIVE_INFINITY in JavaScript. Question: Tell us about the difference between .call() and .apply() functions. Properties are accessible by interacting with the object in Vanilla JS or using jQuery’s prop() method. isNaN() method determines whether a value is NaN (Not-A-Number). Old browsers treat this JS code as a long HTML comment. Question: Explain the use of debuggers in JavaScript? Reference Error – It comes into play when an undeclared variable is used. The general syntax is: Reading a cookie using JS is as simple as creating the same. Question: What are the different types of Error Name values in JavaScript? These are also known as Immediately Invoked Function Expressions and Self Executing Anonymous Functions. These are namely array, current element, and index of the current element.function unque_array (arr){, By using the For loop – In this method of removing duplicate elements from an array, an empty array is used for storing all the repeating, By using Set – This is the simplest approach of removing duplicate elements from an array in JS. Try now. A set is an inbuilt object for storing unique values in an array. As the value of the document. Moreover, the Error object can also be used as a base object for user-defined exceptions. The following example demonstrates using the two functions: Answer: During page loading, the HTML code's parsing is paused by default until the script hasn’t stopped executing. View all posts by the Author. Popping up messages with `alert()` A tried and true method to debug JavaScript items, `alert()` will create a popup alert when your code meets a particular condition. When a function is created inside an expression or another syntax construct, it is called a function expression. In JavaScript the constructors are more similar to normal java constructor. ads via Carbon. The following code snippet demonstrates using a normal function in JavaScript: The aforementioned function can be represented in a better way by using closures. To run your javascript file , you need to go the directory of that javascript file through your terminal and then write “node your_js_file_name_here” in your terminal and hit enter. Question: Can you draw a simple JavaScript DOM (Document Object Model)? A function declaration, on the other hand, can be called before the same is defined. JavaScript is an object-based language based on prototypes, rather than being class-based. isArray() method checks whether the passed variable is an Array object. The loop continues until all the object properties are exhausted. Question: What do you mean by Event Bubbling and Event Capturing? Question: Could you explain escape() and unescape() functions? Define an object constructor, and then create objects of the constructed type. Six additional escape characters are also available in JavaScript: These aren’t in anyway executed in the HTML or JS code. An open, cross-platform scripting language, Designed especially for creating network-centric applications, Range Error – Generated when a number outside the specified range is used. A closure is the combination of a function bundled together (enclosed) with references to its surrounding state (the lexical environment). In object-oriented programming, a class is an extensible program-code-template for creating objects, providing initial values for state (member variables) and implementations of behavior (member functions or methods). Some web browsers don’t let you delete a cookie unless you don’t specify the cookie's path. Question: Can you differentiate between let and var? Strict Mode – When a function declaration is within a code block in the Strict mode, it is visible everywhere inside that block but not outside of it. Answer: There are 6 types of Error Name values. Data doesn't have to be difficult. Cookie object. Consider checking out this excellent udemy course for preparing for an upcoming JS interview: JavaScript Interview Prep: Practice Problems. Question: Could you enumerate the various features of JavaScript? Contrastingly, JS code is meant to run inside a browser only. Using deferred scripts results in a delay in the script's execution when the HTML parser is running. tag. Chrome Developer Tools. The Complete JavaScript Course 2020: Build Real Projects! For example: Answer: The for-in loop is meant to be used for looping through the properties of a JavaScript object—every iteration of the loop results in a property of the object getting associated with the variable name. The function expression is usable only from that moment onwards. Definition – A function declared as a separate statement in the main code flow is termed the function declaration. You need to choose the Console tab to view the result. Its important characteristics are: Answer: JavaScript offers a short and concise way of writing function expressions known as arrow functions. State their various properties. Moreover, they don’t provide support for arguments,, super, and this. The closure contains all local variables that were in-scope at the time of the closure creation. Time of Use – A function expression is created when the execution reaches it. The most basic way of creating a cookie using JS is to assign a string value to the document. Currently working with The document.cookie string keeps a list of name = value pairs, where a semicolon separates each pair. Answer: To read the information from the client’s screen, screen objects are used in JavaScript. Question: Please explain the various JavaScript data types? You can work with functions as if they were objects. Other than the generic Error constructor, JS provides support for 7 error constructors that are: Answer: All modern browsers (Mozilla Firefox, Safari, Google Chrome, etc.) To enable the Strict Mode, one needs to add the string literal “use strict” above the file that needs to be opened in the Strict Mode. Inside the if statement, executing typeof F returns undefined because if the statement code executes at run time, the statement inside the condition is evaluated. Most notable amongst them are listed down as follows: Answer: Following are some of the inbuilt methods in JavaScript: Answer: The Error constructor is responsible for creating an error object. log()` ... How do you check if a value is in an array in JavaScript? We have a variety of advertising options which would give your courses an instant visibility to a very large set of developers, designers and data scientists. To call the filter() method, three arguments are required. Deleting a cookie using JavaScript, simply set the expiration date (expires) to a time that’s already past.