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Tuesday, June 25, 2019

25 Top CoffeeScript Interview Questions and Answers {Updated}

CoffeeScript Interview Questions and Answers for experienced PDF, Read commonly asked CoffeeScript Job Interview Questions with Answers PDF for Freshers.

Read CoffeeScript Interview Questions and Answers

What is CoffeeScript?
CoffeeScript is a small programming language that compiles into JavaScript. It helps to write JavaScript code better by providing you with more consistent syntax and avoiding the irregular nature of JavaScript language

What are the basic rules to remember for Coffee Script?
The basic rule for Coffee Script
  • Whitespace matters: There are no curly braces in CoffeeScript
  • No parentheses: Functions that take arguments do not require parentheses

What are transpilers?
CoffeeScript code has to be translated into JavaScript and to convert this code a tool is required. This tool is known as transpilers.

What are the benefits of Coffee Script over JavaScript?
  • CoffeeScript allows you to express your program with a lot less code than JavaScript
  • It has a lot of lightweight add-ons like Ruby string Interpolation and Python style list comprehension
  • Makes everyday tasks easier to perform with CoffeeScript rather than JavaScript

How variables differ in CoffeeScript than JavaScript?
For variables in JavaScript, you have to add a semi-colon at the end of it to execute while in CoffeeScript there is no need to add Semi-colon at the end of the statement. Unlike, JavaScript, CoffeeScript adds up semi-colon with ease.

Explain functions in CoffeeScript?
Functions in CoffeeScript is an (Optional) list of parameters followed by an arrow and then the function body.
For example, log = (message) à console.log message

How CoffeeScript compiler is helpful in CoffeeScript?
CoffeeScript compiler ensures that within the lexical scope, all your variables are properly declared, and you never need to write “var” yourself

What are the two different kinds of loops does CoffeeScript provide?
Like JavaScript, CoffeeScript also provides two different kinds of loops
  • One for iterating over an array
  • One for iterating over the properties of an object

What is Splat in CoffeeScript?
Splat is the term used for ( . . . ) operator for var-argument. Splatted arguments can come either before, after or between standard arguments.
For example, (first, rest . . . )

Explain how you can define a range array in CoffeeScript?
In two ways, you can define a range array in CoffeeScript
  • Inclusive range: This range is always defined by the (. . ) operator
  • Exclusive range: This range is always defined by (. . . ) and it always omits the last value
For example, myArray = [ 1..10 ] & myArray = [ 1. . . 10 ]

What is the use of CoffeeScript’s chained comparison syntax?
CoffeeScript’s chained comparison syntax is used to know whether any given variable falls inside a given range and also it enables to chain the two comparisons together in a form that matches closely.

Explain about class methods in CoffeeScript?
CoffeeScript store class object on the object itself rather than on the object prototype, which saves memory and gives a central location to store class-level values

Explain how you could do Callback binding in CoffeeScript?
In order to bind a callback function to an object you can use the fat arrow (=>) instead of the normal arrow (à), the function gets automatically bound to the object.
For example, $ ( ‘.product’ ). Click ( event ) =>

In CoffeeScript how clone-function is useful?
The clone function is useful in creating a completely new object in Coffee Script by
  • Copying all attributes from the source object to the new object
  • Repeating the steps of copying attributes from the source object for all sub-objects by calling the clone-function
  • Creating a new object as the source object

What is the difference between copying an object through assignment and clone-function?
The difference between copying an object through assignment and clone function is that how they handle references. The assignment only copies the object’s references while clone-function creates a completely new object.

How you can replace a portion of a string with another value?
To match and replace a portion of a string with another value, Regular Expression can be used.

How CoffeeScript interpolates the strings?
CoffeeScript interpolates the strings in the same fashion as ruby; most expressions are valid inside the # {. .. } interpolation syntax

How does Boolean work with CoffeeScript?
Booleans in CoffeeScript is same as other but instead of “True” or “False” it is more likely represented as “on” or “Yes” instead of true while “off” or “No” instead of false.

How you can detect and create a missing function in CoffeeScript?
To detect and create a missing function in CoffeeScript, you can use the existential assignment operator (?=)

Can you bind parameters to properties in CoffeeScript?
Yes, CoffeeScript allows to bind parameters to properties by using the @ shorthand, this also allows you to define class functions.

In CoffeeScript how you can search a substring and how you can return either the starting position of the match or the matching value itself?
There are several methods for doing this using regular expressions. Some methods are called on a RegExppattern or object while some are called on String objects.
  • RegExp objects: One way is to call the test method on a RegExp pattern or object. The test method returns a boolean value
  • String objects: The match method matches the given string with the RegExp.

How you can call a function from within that same function in CoffeeScript?
To call a function from within that same function, you can use @arguments.callee for unnamed function while named functions keep their purpose explicit and make more of a code. The arguments.callee allows for the recursion of an anonymous function.

How can you map an array in CoffeeScript?
CoffeeScript has clean support for anonymous functions, to map an array in object use map() with an anonymous function. For simple mapping, list comprehension is more useful as CoffeeScript directly support list comprehensions.

Explain how you can use arrays to Swap variables?
To swap variables using an array, you can use CoffeeScript’s destructuring assignment syntax, it allows swapping two values without the use of a temporary variable.

What is the use of Existential Operators in CoffeeScript?
Existential Operators in CoffeeScript can be used for
  • To check the existence of a variable
  • For conditional assignment
  • For function chaining

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