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