Pyjamas

• Introduction
• Installation
• Example
• Functions
  • isFalsy
  • isEmpty
  • isInt
  • isFloat
  • isNumber
  • isString
  • bool
  • sum
  • int
  • len
  • range
• Testing

---

This package brings some Python beauty to JavaScript, which mostly includes typing utils that help you get less exceptions and have more control of your codes functionality. As you probably know, JS is dynamically typed which sometimes leads to unwanted behaviours, this package is trying to solve these problems with a new implementation of falsy values and typing utils. Here is a comparision:

These values will make bypass the if blocks in JavaScript

if (false)
if (undefined)
if (0)
if (0n)
if (null)
if (NaN)
if ('')

Now Pyjamas extends these values and also consideres the following values as falsy

// Empty Arrays
[]

// Empty Objects
{}

// Functions that return falsy values or throw an exception
() => null

Installation

use

yarn add pyjamas

or

npm install pyjamas

Example

Pyjamas ships with the isFalsy and bool function which is just an inverter of isFalsy

# ES6
 
import { isFalsy, bool } from 'pyjamas'
 
if(isFalsy(undefined)) {
  // this will execute because undefined is Falsy
}
 
if(bool(undefined)) {
  // this won't execute because bool will convert undefined to false
}

isFalsy(value)

Function	Returns
isFalsy(undefined)	true
isFalsy(false)	true
isFalsy(NaN)	true
isFalsy('')	true
isFalsy({})	true
isFalsy([])	true
isFalsy(0)	true
isFalsy(0.0)	true
isFalsy([][0])	true
isFalsy([].length)	true
isFalsy(() => [][0].name)	true
isFalsy(NaN)	true
isFalsy('hi')	false
isFalsy(9)	false
isFalsy(0.0000000001)	false
isFalsy({ none: 'none' })	false
isFalsy(() => [{ name: 'pete' }][0].name)	false

Especially usefull is that you can check for a value in an array of objects for instance [][0].name howerver just putting it in isFalsy like: isFalsy([][0].name) would throw an exception, you need to write () => in front of the value.

isEmpty(value)

this function checks if a String | Array | Object is empty

Function	Returns
isEmpty('Hi')	false
isEmpty({ hi: 'hi })	false
isEmpty([0,1,2])	false

ANYTHING else returns true

isInt(value)

Check if the value is an Integer

Function	Returns
isInt(1)	true
isInt(0)	true
isInt(2 / 2)	true
isInt(1.0)	true
isInt(2 / 1.5)	false
isInt(1.000000000001)	false
isInt('1')	false
isInt(NaN)	false
isInt(0.999999999999)	false

isFloat(value)

Check if the value is a Float

Function	Returns
isFloat(1.1)	true
isFloat(0.000000001)	true
isFloat(2 / 2.1)	true
isFloat(1)	false
isFloat(0)	false
isFloat('1')	false
isFloat(NaN)	false
isFloat(undefined)	false

isNumber(value)

check if value is either an Interger or a Float

isString(value)

check if value is a String

Function	Returns
isString('')	true
isString('String')	true
isString(undefined)	false
isString(null)	false

Converters

Methods that parse the arguments into defined data structures

bool(value)

bool uses isFalsy to parse the incoming value into a boolean

len(value)

get the length (Integer) of an Array | String | Object

Function	Returns
len('Hi')	2
len([0, 1])	2
len({ a: 'a', b: 'b' })	2
len('')	0
len([])	0
len({})	0
len(NaN)	-1
len(undefined)	-1
len(false)	-1
len(null)	-1

sum(value)

add all values inside an Array

Function	Returns
sum([1, 1])	2
sum([0.5, 0.5])	1
sum([1, null])	1
sum(undefined)	0
sum([null, NaN])	0
sum('Hi')	0

int(value)

Trys to parse anything to an Integer, else returns 0

Function	Returns
int(1)	1
int(1.0)	1
int('1')	1
int(1.999999999)	1
int(0.999999999)	0
int('NotaNumber')	0
int(undefined)	0
int(NaN)	0

float(value)

Trys to parse anything to a Float, else returns 0.0

Function	Returns
float(1)	1.0
float('1.1')	1.1
float('1')	1.0
float(' 1.2 ')	1.2
float('1.2 m')	1.2
float('NotaNumber')	0.0
int(undefined)	0.0
int(NaN)	0.0

range(start: int, stop: int)

generate an Array with start as the Integer to begin with and Stop as the Index to end with

Function	Returns
range(2)	[0, 1]
range(10).length	10
range(5, 10)	[5, 6, 7, 8, 9]

Testing

This package is heavily tested and tries to cover every possible scenario with unit test, in case you should find something we didn't thought about please contact us. We are much obliged for your help.