Let us start with JavaScript questions that are suited for young graduates and freshers in the domain with little to no work experience:
Debugger is a JavaScript component developers activate to debug their code. Systems may have in-built debuggers that can be turned on and off at the right time, requiring developers to report faults. Under such a situation, the code’s remaining section should stop execution before getting to the next line while debugging.
In JavaScript, both of these operators are comparison operators. While the “==” operator is used for comparing values, the “===” operator is used to compare values and types.
In JavaScript, the “var” keyword is used from the beginning, while the “let” keyword was added much later in 2015. The “var” keyword holds a function scope. The variable you specify anywhere in the function using “var” is accessible. On the other hand, a variable scope declared with the “let” keyword is limited to the block where it is declared.
JavaScript is a dynamically typed programming language for building web applications. Here, developers check the type of a variable during run-time. On the other hand, the type of a variable in a statically typed language is checked during compile-time. Being a dynamically typed language, the variables in JavaScript are not related to any type, making them hold values of any data type.
The strict mode is a new feature launched in ECMAScript 5 that allows developers to write a function or a code in a strict operational environment. Mostly, the programming language is not too “severe” with regard to throwing errors. However, in the strict mode, all error forms (including silent errors) are thrown. This makes debugging a lot simpler for developers.
Here are some of the most important characteristics of the strict mode in JavaScript:
In JavaScript, self-invoking functions are the functions where self-invoking expressions are automatically invoked without being requested. A function expression will execute automatically if it is followed by (). It is also important to note that a function declaration is not capable of being invoked by itself.
Generally, a JavaScript developer declares and calls a function. However, they may use anonymous functions to automatically run a function when it is described. It is not called again and these functions have no names.
Let us now move on to advanced JavaScript interview questions suited for experienced professionals with sufficient work experience in the domain:
Arrow functions are the JavaScript functions launched in the programming language’s ES6 version. They provide users with a newer and shorter syntax to improve declaring functions. Developers can use these functions only as a function expression.
Arroe functions can be declared without the function keyword. In the case of a single returning expression, there is no need to use the return keyword in an arrow function. Moreover, you can remove the {{ '{ }' }} braces in the case of functions having a single line of code.
In JavaScript, the prototype design pattern is used to produce different objects. Instead of returning uninitialized objects, the design pattern creates objects with values replicated from a template - or sample - object.
A good example of prototype patterns in JavaScript coming in handy is the introduction of business objects with parameters. Here, the new business object’s default settings are stored in the concerned prototype object. The prototype design pattern is rarely used in traditional programming languages. However, it is used to create new objects and templates in JavaScript as it is a prototypical language.
Here are the different methods used to declare or construct a JavaScript object:
In JavaScript, promises are used by developers to handle asynchronous operations. Before the introduction of promises, developers used callbacks for this function. However, the limited functionality of callbacks often led to unmanageable code if multiple callbacks are used..
A JavaScript promise has four different states:
Over time, JavaScript has stayed in tune with the ongoing tech trends in the industry. Since its launch in 1995, the programming language has made responsive design easier. It gives internet users a seamless experience through an interactive user experience.
The salary of a JavaScript developer in India can range from ₹2 lacs to ₹12 lacs, making the average annual salary around ₹4.5 lacs. This package can increase for experienced professionals who choose to upskill themselves.
Here are some of the most popular companies that use JavaScript to build their web applications:
JavaScript has stayed relevant for organizations and developers for almost three decades and it is likely to continue its prominence in the industry. If you stay in sync with the current industry trends and upskill yourself, securing a job as a JavaScript developer can future-proof your career. Companies will always need skilled developers for their web applications and you will always be of immense value to them.
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