Custom Encoder

Encoder from integers to any custom base and vice-versa

Installation

npm install --save custom-encoder

Usage

The package exports a function that generates the encoder. you can simply call the generator to store the encoder itself --as in example 1--, or you can store the function and call it each time you need a new encoder --as in example 2--.

// Require the package
const encoder = require('custom-encoder')();

// Set a new base
encoder.setBase(myCustomBase);

// Encode an integer to the current base
let myIntEncoded = encoder.encode(myInt);

// Decode from a String according to the current base
let myDecodedInt = encoder.decode(myIntEncoded);

// Get the current base as a string
let myBase = encoder.getBase();

You can create more than one encoder if you need to use more than one different base at the same time.

const encoderGenerator = require('custom-encoder');
const encoder1 = encoderGenerator();
const encoder2 = encoderGenerator();

encoder1.setBase(2);
encoder2.setBase('ab');

console.log(encoder1.encode(10)); // prints: '1010'
console.log(encoder2.encode(10)); // prints: 'baba'

API

The API is very simple. There are four methods:

• encoder.setBase()
• encoder.encode()
• encoder.decode()
• encoder.getCurrentBase()

encoder.setBase()

Set the base that will be used by functions encode and decode.

Syntax

encoder.setBase(base)

Params

base
It can be either one of the numbers 2, 8, 10, 16, or a string. If the value given is a number, it sets the base to the following symbols:

• 2: 01
• 8: 01234567
• 10: 0123456789
• 16: 0123456789abcdef

If the value given is a string, it must contain the symbols of the base ordered from less value to more value.

Throws

It trows the following errors:

• TypeError: If base is not 2, 8, 10 or 16, it must be a string.
• Error: All symbols in the base must be unique.
• Error: The base must have at least two different valid symbols.

Example

// Set the base to binary
encoder.setBase(2);

// Set the base to hexadecimal
encoder.setBase(16);

// Set a custom base where the symbol 'b' is one unit bigger than 'a', and
// symbol '1' is one unit bigger than 'd'
encoder.setBase('abcd1234') 

encoder.encode()

Encodes the given integer according to the current base.

Syntax

encoder.encode(intNumber)

Params

intNumber
Is the number given to be encoded. It must be an integer, or the function throws an error.

Returns

It returns a string with the encoded value of intNumber according to the current base.

Throws

It trows the following error:

• TypeError: The given number intNumber must be an integer.

Example

// Set the base to binary
encoder.setBase(2);
encoder.encode(10); // result: '1010'

// Set the base to hexadecimal
encoder.setBase(16);
encoder.encode(195951310); // result: 'badface'

// Set a custom base
encoder.setBase('myfriend');
encoder.encode(481); // result: 'diy'

encoder.decode()

Decodes the given string according to the current base.

Syntax

encoder.decode(codedString)

Params

codedString
Is the string given to be decoded. The user is the responsible to check that the base used to encode is the same being used to decode.

Returns

It returns the integer corresponding to the given encoded string according to the current base.

Throws

It trows the following errors:

• TypeError: The input must be a string.
• Error: The input contains symbols that are not in the base.

Example

// Set the base to binary
encoder.setBase(2);
encoder.decode('1010'); // result: 10

// Set the base to hexadecimal
encoder.setBase(16);
encoder.encode('badface'); // result: 195951310

// Set a custom base
encoder.setBase('myfriend');
encoder.encode('diy'); // result: 481

encoder.getCurrentBase()

Returns the current base as a string of the symbols used.

Syntax

encoder.getCurrentBase()

Returns

A string with the symbols in the current base, ordered from smaller to bigger value in the base.

Example

// Set the base to binary
encoder.setBase(2);
encoder.getCurrentBase(); // result: '01'

// Set the base to hexadecimal
encoder.setBase(16);
encoder.getCurrentBase(); // result: '0123456789abcdef'

// Set a custom base
encoder.setBase('myfriend');
encoder.getCurrentBase(); // result: 'myfriend'