Simple calculation lib with lazy feature

vue-lazy-calc

this is a simple calculation plugin in lazy way. (inspired by lodash)

features

• vue friendly
• strong typed
• lazy evaluation
• chaining methods
• code coverage 100%

TODO:

• [x] seperate simple lazy class from base class
• [x] support more operator in stream api

Install

npm install vue-lazy-calc --save

Quick Start

import lzCalc from "vue-lazy-calc"
Vue.use(lzCalc)

Methods

• this.$lzCalc in Component context.
• Vue.$lzCalc in global.

API list

base

export declare class LazyBase {
  lazy(init?: number): LazyCalc
  stream(s?: LazyCalc): LazyStream
}

• lazy => init a new instance with optional initValue
• stream => init a stream to operate between multiple lazy instance with optional init instantce

simple

export declare class LazyCalc {
  add(y: number): LazyCalc
  divide(y: number): LazyCalc
  subtract(y: number): LazyCalc
  multiply(y: number): LazyCalc
  do(fn: operatorFunc): LazyCalc
  ceil(precision?: number): LazyCalc
  floor(precision?: number): LazyCalc
  round(precision?: number): LazyCalc
  default(fallback: any): LazyCalc
  value(): any
}

• add/subtract/divide/multiple => + - * / (simple calculation) between numbers
• round/floor/ceil => deal with precision of the float number
• value => excute the declared method chain
• default => set default value if previous operations get NaN
• do => accept a custormized function for the number

Examples

(1+3)*2/3 with precision 2

const result = this.$lzCalc
  .lazy(1)
  .add(3)
  .multiply(2)
  .divide(3)
  .round(2)

console.log(result.value()) // 2.67

const addThree = result.add(3)
console.log(addThree.value()) // 2.67+ 3 =>5.67

Stream

declare class LazyStream {
  add(y: LazyCalc): LazyStream
  subtract(y: LazyCalc): LazyStream
  multiply(y: LazyCalc): LazyStream
  divide(y: LazyCalc): LazyStream
  round(precision?: number): LazyStream
  ceil(precision?: number): LazyStream
  floor(precision?: number): LazyStream
  do(fn: operatorFunc): LazyStream
  default(fallback: any): LazyStream
  value(): any
}

const result = this.$lzCalc
  .lazy(1)
  .add(3)
  .multiply(2)
  .divide(3)
  .round(2)

const tmp = this.$lzCalc.lazy(2).add(3)
const s = this.$lzCalc.stream(result).add(tmp)

console.log(s.value()) // 2.67 + 5 => 7.67

1. when declare the result variable, no calculation excuted until value()
2. you can reuse the declare variable

GitHub