Updated June 21, 2023
Introduction to ES6 Interview Questions and Answers
If you are looking for a job related to ES6, you must prepare for the 2023 ES6 Interview Questions. Every interview is different from the different job profiles, but still, to clear the interview, you need to have a good and precise knowledge of ES6 processes. Here, we have prepared the critical ES6 Interview Questions and answers that will help you succeed in your interview.
ES6, also known as ECMAScript 2015, is a standardized version of JavaScript that ECMAScript International released in 2015. ECMAScript International defined it as a scripting language. JavaScript is a scripting language that is widely used on both the client side and server-side. ES6 introduced many new features that make the language more flexible and powerful. However, not all browsers support ES6 fully yet.
Part 1 – ES6 Interview Questions (Basic)
This first part covers basic ES6 Interview Questions and Answers.
Q1. Define ES6 and mention the new features of ES6.
Answer:
Refer to the introduction part for the definition of ES6. Below are the new features listed:
- Constants (Immutable variables)
- Scoping
- Arrow functions
- Extended parameter handling
- Template literals
- Extended literals
- Modules
- Classes
- Enhanced Regular expressions
- It enhanced object properties.
- Destructuring Assignment
- Symbol Type
- Iterators
- Generator
- Map/Set & WeakMap/WeakSet
- Typed Arrays
- Built-in Methods
- Promises
- Metaprogramming
- Internationalization and Localization.
Q2. How do you use ES6, or is the best way to use ES6 in a project?
Answer:
As mentioned, all the browsers do not support ES6, so to use the ES6 script, we need to convert it into the ES5 script supported by all browsers. To convert into a pre-ES6 hand, we required transpilers like Babel. Babel is a popular javascript transpiler used for this purpose, allowing ES-6 code to transform into an ES-5 script to support all browsers.
Let us move to the following ES6 Interview Questions.
Q3. What are the Constants in ES6?
Answer:
Constants are also referred to as Immutable variables. It means that the value of a constant variable cannot be changed. The value assigned at the time of the declaration remains unchanged. E.g., For const X= 5.0, here the value of X remains 5 every time, and it cannot be changed.
Q4. What are Block Scoped variables and functions?
Answer:
Interviewers often ask about a common ES6 feature: defining variables and functions as indefinite blocks. You can use these blocks within the scope where you define or declare them. If you declare a variable or function within a function block, it will have a limited scope and cannot be accessed outside of it. The ‘const’ keyword prevents changing the value of a variable, while the ‘let’ keyword enables re-assigning the variable value, even within loops or arrays.
Q5. Explain briefly about Arrow functions.
Answer:
Arrow functions support expression bodies and statement bodies, which return the expression’s value and make the syntax more expressive. Arrow functions have a lexical ‘this’ feature as well. Arrow (=>) is used as part of the syntax. Lexical is declared or defined where the function is written. It comes under the umbrella of lexical scope; lexical scope has access to variables in its parent scope.
Part 2 – ES6 Interview Questions (Advanced)
Let us now look at the advanced ES6 Interview Questions and Answers.
Q6. Explain Webpack and the benefits of using Webpack.
Answer:
Webpack bundles javascript files that can be used in a browser. Webpack processes the application and builds a dependency graph to map each module of the project requirement and generate the bundles. It allows you to run the environment that Babel has hosted. The advantage of using a web pack is that it bundles multiple modules and packages into a single JavaScript file. It integrated the dev server, which helps update code and asset management.
Q7. Explain Default parameter values, Rest parameter, and Spread operator.
Answer:
You can use default parameter values to initialize functions with default values. The value of a parameter can be anything like a null value, number, or process.
The rest parameter retrieves all the arguments to invoke the function. It means we can push the items of different categories separately. The rest parameter uses the rest parameter to combine parameters into a single array parameter.
The spread operator is denoted by ‘…’, followed by the variable name. For example, the syntax for the spread operator is ‘…x’. It is used in ES6 to manipulate objects and arrays, and to copy enumerable properties from one object to another.
Let us move to the following ES6 Interview Questions.
Q8. Explain Internationalization and localization.
Answer:
These APIs are standard API of JavaScript that helps in different tasks like collation, Number formatting, Currency formatting, and Date and time formatting.
- Collation: It can search within a set of strings and sort them based on a specific locale. It is Unicode-aware.
- Number formatting: It can format numbers with localized separators and digit grouping. Other options include style formatting, numbering system, percent, and precision.
- Currency formatting: It can format numbers with currency symbols, localized separators, and digit grouping.
- Date and time formatting: It can format dates and times with localized separators and ordering. The format can be short or long, supporting parameters such as locale and time zone.
Q9. What is a Destructuring assignment, and explain in brief?
Answer:
In an interview, interviewers frequently ask about using destructuring assignments to bind a set of a variable to the corresponding values. It mainly refers to using patterns to extract an object’s parts. A destructuring assignment has different forms array matching, object matching, shorthand notation, object matching, deep matching, object and array matching, default values, parameter context matching, and fail-soft destruct.
- Array matching/object matching, shorthand notation/ object matching, deep matching: It is intuitive and flexible to arrays into individual variables during an assignment.
- Object and Array matching: It is simple and defined default values for destructuring of objects and arrays.
Q10. Explain briefly about classes, modules, and proxies.
Answer:
Object-oriented programming (OOP) style is the foundation of classes. The class declaration makes the patterns easier to use. It supports inheritance, base class access, static methods, and constructors.
- Modules: it defines the patterns from popular javascript module loaders. It supports exporting or importing the values from or to modules without the global namespace. It supports marking the deal as the default shipped value and max-min values.
- Proxies: It enables object creation with various behaviors available to host objects.
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