epam-short-track

Task 6. JS Classes & Inheritance

Folder Name	Branch	Coefficient
/js-classes	js-classes	0.4

Task Description

In a single file index.js, implement a base class with common methods and two child classes:

• BaseBuilder (common methods ES5 style)
• IntBuilder (ES6 style)
• StringBuilder (ES5 style)

All three classes must be implemented in one index.js file using JavaScript.
Almost all methods should support chaining.
You may add your own methods and properties, but the methods described below are mandatory.

Implementation Requirements

• One index.js file in the js-classes folder.
• One base class with common methods:
  • BaseBuilder — implemented in ES5 style (using function constructor and prototype).
• Two child classes inheriting from the base:
  • IntBuilder — implemented in ES6 style (using class).
  • StringBuilder — implemented in ES5 style (using function constructor and prototype).
• All methods except get and static methods must support chaining.
• Methods must match the API below.
• Lazy evaluation: calculations are performed only when get() is called.
• The code must be clean, readable, and follow best practices.

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API

IntBuilder (ES6 class)

// API:
new IntBuilder(int) // constructor takes starting integer, if not provided starts with 0
.plus(...n)         // takes any number of integers and adds them to the value
.minus(...n)        // takes any number of integers and subtracts them from the value
.multiply(n)        // multiplies the value by n
.divide(n)          // leaves the integer part of dividing the value by n
.mod(n)             // leaves the remainder of dividing the value by n
.get()              // returns the current value
IntBuilder.random(from, to) // static method, returns a random integer in the range [from, to]

Example:

IntBuilder.random(10, 100); // 42

const intBuilder = new IntBuilder(10); // 10
intBuilder
  .plus(2, 3, 2)    // 17
  .minus(1, 2)      // 14
  .multiply(2)      // 28
  .divide(4)        // 7
  .mod(3)           // 1
  .get();           // -> 1

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StringBuilder (ES5 function + prototype)

// API:
new StringBuilder(str)   // constructor takes starting string, if not provided starts with ''
.plus(...str)            // takes any number of strings and concatenates them to the value
.minus(n)                // cuts off n characters from the end of the string
.multiply(int)           // repeats the string int times
.divide(n)               // leaves the first k characters, where k = Math.floor(str.length / n)
.remove(str)             // removes all occurrences of substring str (without using replace)
.sub(from, n)            // leaves a substring starting from 'from' of length n
.get()                   // returns the current value

Example:

var strBuilder = new StringBuilder('Hello'); // 'Hello'
strBuilder
  .plus(' all', '!')     // 'Hello all!'
  .minus(4)              // 'Hello '
  .multiply(3)           // 'Hello Hello Hello '
  .divide(4)             // 'Hell'
  .remove('l')           // 'He'
  .sub(1,1)              // 'e'
  .get();                // -> 'e'

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Implementation Details

• All classes must be implemented in a single index.js file in the js-classes folder.
• No need to export anything.
• Test the classes locally with the examples above before submitting your PR.

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Pull Request Requirements

Your Pull Request must include:

• Task URL.
• Brief description of the implemented classes and their methods.
• Submission date / deadline.
• Your self-check using checkboxes.

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Mentor Checklist

Maximum Score: 100 points

Criteria	Points
The branch is named js-classes	2
Commit messages follow RS School Git Convention	5
The js-classes folder exists	2
The index.js file exists in the correct folder	2
All three classes are implemented in the file	2
Base class is implemented and contains common methods	4
Two child classes are implemented and inherit from the base	15
All methods except get and static methods support chaining	10
All methods described in the task are implemented	20
Lazy evaluation is implemented	20
Code is well-structured, readable, and follows best practices	10
PR description includes:
Task URL	2
Description of classes and methods	2
Submission and deadline dates	2
Your self-check using checkboxes	2
Penalty:
Fewer than 3 commits in the PR	-20
Commit after the deadline and before mentor review	-20
The solution contains comments	-50
The solution contains console.log	-10
The PR includes more than one required index.js file	-50

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Notes

• The solution must be clean, readable, and follow best practices.
• If any required element is missing or implemented incorrectly, points will be deducted accordingly.
• All requirements regarding style and API are mandatory.

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