@logdna/stdlib

stdlib

Standardized modular package exposing language constructs - free of business logic.

Main Goals

Free of business logic
Consistent api
Explicitness
Lacking in dependencies
Lacking indirection
Highly debuggable
Highly testable

Installation

> npm install @logdna/stdlib

API
Authors
Contributors ✨

API

array

Common array manipulation functions

`toArray`(item: `any`): Array

Converts or wraps anything in an array. Set objects will be converted to arrays. A String will be treated as a CSV and parsed into an array. If an array cannont be coerced from the input value, it will be wrapped in an a single element array

Arguments:

item - The element to convert to an array.

returns result Array: The resulting array for input coercion

Example

const {array} = require('@logdna/stdlib')
array.toArray() // []
array.toArray(null) // []
array.toArray(1) // [1]
array.toArray('1,2, 4, 3') // [1, 2, 4, 3]

iter

Iteration tools for complex and efficient iteration. Inspired by python's itertools

`cycle`(items: Array): Generator

Iterates endlessly over a single array of items. The elements of the array can be of any type.

Arguments:

items (Array) - An array to iterate over

returns Generator A generator object containing the passed in elements

Example

const {iter} = require('@logdna/stdlib')
const numbers = iter.cycle([1, 2, 3])

numbers.next().value // 1
numbers.next().value // 2
numbers.next().value // 3
numbers.next().value // 1
numbers.next().value // 2
numbers.next().value // 3

json

Common json functions

`parse`(input: String): Object

Safe json parsing function that attempts to json parse a string. If it cannont, undefined will be returned

Arguments

input (String) - a json string to parse

returns Object A fully parsed javascript object

Example

const {json} = require('@logdna/stdlib')
json.parse('{"valid": "json"}') // {valid: 'json'}
json.parse('{"invalid" json') // undefined

object

Common object manipulation and intropsection functions

`has`(obj: Object, property: String [, separator: String = '.']): Boolean

Determines if a specified key is a direct property of an object. This function is safe to call on objects that do not inherit from Object.prototype, unlike attempting to call .hasOwnProperty on input objects

Arguments

obj (Object) - The object to introspect
key (String) - The name of the property to locate
(optional) separator (String) - Delimiter character
- default: '.'

returns Boolean - True of the key is defined on the input object.

Example

const {object} = require('@logdna/stdlib')
object.has({a: 1}, 'a') // true
object.has({}, 'test') // false
object.has(Object.create(null), 'test') // false
object.has({}, 'hasOwnProperty') // false
object.has({one: {two: {three: 3}}}, 'one-two-three', '-') // true

`get`(obj: Object, property: String [, separator: String = '.']): any

Returns the value from an object at a specified object path.

Arguments

obj (Object) - The object to introspect
key (String) - The name of the property to local
(optional) separator (String) - Delimiter character
- default: '.'

returns any - The value at the specified key. If no value is found, undefined will be returned.

Example

const {object} = require('@logdna/stdlib')
const obj = {one: {two: {three: 3}}}
const value = object.get(obj, 'one-two-three', '-') // 3

`set`(obj: Object, property: String, value: `any` [, separator: String = '.' ]): Object

Sets a property at the deepest level. Nested objects will be created if they do not exist. Returns the modified object. This will not work on complex Types like arrays or maps. Only POJOs

NOTE: if you find your self wanting to set the value at a specific index of an array - you probably want an object.

Arguments

obj (Object) - The object to introspect
key (String) - The name of the property to local
value (any) - The value to set at the specified path
(optional) separator (String) - Delimiter character
- default: '.'

Example

const {object} = require('@logdna/stdlib')
const obj = {one: {two: {three: 3}}}
const value = object.set(obj, 'four.five', 6)
// {one: { two: three: 3 }, four: {five: 6}}

`filter`(obj: Object, test: Function): Object

Similar to array.filter, removes keys from an input object that do not pass the test function

NOTE: This function returns a null object - Object.create(null) which does not inherit from Object.prototype

Arguments

obj (Object) - The object to introspect
test (Function) - The function to be used to reject keys from the input object. If this function returns a truthy value, the key will be included in the final output. If falsey it will be excluded

Example

const {object} = require('@logdna/stdlib')
const obj = {one: { two: three: 3 } }

object.filter({two: 2, three: 3}, (key) => {
   return key.match(/ee$/)
}) // {three: 3}

returns Object An object containing only the keys which passed the test function. The return object will have a null prototype.

`typecast`(obj: Object [, depth: Number = 1000]): Object

Recursively typecast string values of enumerable object properties, using string.typecast()

Arguments

obj (Object) - The input object
key (Number) - The maximum depth to recursively typecast

returns Object A new object with all string properties typecast.

Example

const {object} = require('@logdna/stdlib')
const obj = {foo: '1', bar: 'null', baz: 'three', qux: {foo: '2'}}
const casted = typecast(obj)
// {foo: 1, bar: null, baz: 'three', qux: {foo: 2}}
const with_depth = typecast(obj, 0)
// {foo: 1, bar: null, baz: 'three', qux: {foo: '2'}}

string

`camelcase`(text: String): String

Casts a string value to its camel case variant

Arguments

str String - The string value to convert

returns String A camelcase version of the input string

Example

const {string} = require('@logdna/stdlib')
string.camelcase('Hello George Washington') // helloGeorgeWashington

`lowercase`(text: String): String

A safe alternative to String.prototype.toLowerCase(). This can be called non string inputs and they will be converted to string prior to lower casing.

Arguments

str String - The string value to convert

returns String A lowercased version of the input string

Example

const {string} = require('@logdna/stdlib')
string.lowercase('Hello George Washington') // hello george washington
string.lowercase({}) // [object object]
string.lowercase(null) // ''
string.lowercase(undefined) // ''

`uppercase`(text: String): String

A safe alternative to String.prototype.toUpperCase(). This can be called non string inputs and they will be converted to string prior to upper casing.

Arguments

str String - The string value to convert

returns String A uppercased version of the input string

Example

const {string} = require('@logdna/stdlib')
string.uppercase('Hello George Washington') // HELLO GEORGE WASHINGTON
string.uppercase({}) // [OBJECT OBJECT]
string.uppercase(null) // ''
string.uppercase(undefined) // ''

`slugify`(text: String [, separator: String = '-']): String

Converts a string to a url friendly format by replacing spaces and symbols with a known value and converting to lower case

Arguments

str String - The string value to convert
(optional) separator (String) - Delimiter character
- default: '-'

returns String A slugified version of the input string

Example

const {string} = require('@logdna/stdlib')
string.slugify('A fake Sentence') // a-fake-sentence
string.slugify('A fake Sentence', '::') // a::fake::sentence

`typecast`(text: String): Object

Best effort to cast a string to its native couter part where possible. Supported casts are booleans, numbers, null and undefined

Arguments

value - The value to cast

returns The native representation of the string input. If the value could not be cast, it will be returned as it was passed.

Example

const {string} = require('@logdna/stdlib')
string.typecast('null') // null
string.typecast('true') // true
string.typecast('10.01') // 10.01
string.typecast({}) // {}

`typeOf`(element: `any`): String

A more accurate version of the javascript built-in function typeof

Arguments

input - The input object to introspect

returns String A normalized string representation of the input object

Example

const {typeOf} = require('@logdna/stdlib')
typeOf(new Date()) // 'date'
typeOf(/\w+/) // regexp
typeOf(() => {}) // function
typeOf(new Set()) // set

`Callable`: Class

A class object whose instances are derived from Function and can be called. When exteded, a Symbol function defined by Symbol.for('call') will be executed with any arguments that were passed

Example

const {Callable} = require('@logdna/stdlib')
const __call__ = Symbol.for('call')
class Hello extends Callable {
  constructor(opts) {
    this.yell = !!opts.yell
  }
  [__call__](name) {
    const output = `Hello, ${name}`
    console.log(this.yell ? `${output.toUpperCase()}!` : output)
  }
}

const screamAt = new Hello({yell: true})

screamAt('bill') // HELLO, BILL!