ParsaJS

https://parsajs-demo.netlify.app/

Library to parse and evaluate arithmetic expressions without eval()

Supports basic operators [ ** * / % + - ( ) ] and variables.

Order of operations: BEMDAS

Usage

$ npm i @jaakkohurtta/parsajs

import Parsa from "@jaakkohurtta/parsajs"
const myParser = new Parsa()

let parse = myParser.parse('a*(20/8)*b,{"a":3,"b":2}')
let evaluation = myParser.evaluateAll()

console.log(evaluation)
	
// Log:
//	{
//	  complete: true,
//	  eval: 15, 
//	  items: [{ "15", "number" }]
//	  blocks: [{ id: 1, prio: 0, startIndex: 0, endIndex: 0 }],
//	}

Methods

parse(string)

Parses an input string for evaluation

Params: a string
Returns an object: 
	{ 
  success: boolean,
	  msg: string, 
	}

evaluateAll()

Evaluates the expression string

Returns an object: 
	{ 
	  blocks: [{ ... }], 
	  complete: boolean (true), 
	  eval: number, 
	  items: [{ ... }] 
	}

evaluateNext()

Evaluates the next block according to order of operations

Returns an object: 
	{ 
	  blocks: [{ ... }], 
	  complete: boolean (false), 
	  eval: number, 
	  items: [{ ... }] 
	}

Getters

myParser.getSourceString

Returns the original input string

myParser.getItems

Returns an array of parsed expression items

myParser.getNextBlockId

Returns the id of the next block to be evaluated

myParser.getBlocks

Returns an array of parsed items organized in blocks

Tests

$ npm run test

PASS  tests/parsa.test.ts
  Parser tests
    ✓ Simple expression parsed correctly (3 ms)
    ✓ Intermediate expression parsed correctly (1 ms)
    ✓ Complex expression parsed correctly (1 ms)
    ✓ Expressiong with variables is parsed correctly (3 ms)
    ✓ Parsing fails if expression string containains NaNs
    ✓ Parsing fails with if expression starts with operator
    ✓ Parsing fails with if expression ends with operator
    ✓ Parsing fails with if an operator is misplaced (double operator)
    ✓ Parsing fails with odd number of parenthesis (1 ms)
  Eval tests
    ✓ Simple expression is evaluated correctly (1 ms)
    ✓ evaluateNext() works correctly (1 ms)
    ✓ Complex expression with variables is evaluated correctly (1 ms)
  Getters
    ✓ getSourceString returns correct value
    ✓ getItems returns correct values (1 ms)
    ✓ getBlocks returns correct values
    ✓ getNextBlockId returns correct value (1 ms)

Test Suites: 1 passed, 1 total
Tests:       16 passed, 16 total
Snapshots:   0 total
Time:        1.572 s, estimated 2 s

License: MIT