parsemath
Simple parser for arithmetic expressions.
- Written in typescript.
- No dependencies.
- Designed to safely parse untrusted expression strings. Identifiers, operations, and functions can be restricted.
- Supports the following operations:
+
(unary and binary),-
(unary and binary),*
,/
,^
,**
, and=
(equality, not assignment). - Supports variable substitution (see below).
- Whitespace insensitive.
Installation
npm install parsemath
Use
import {parse} from "parsemath" // or let {parse} = require("parsemath")
let value = parse("x^2 + x + 1", {x: 1e-1})
console.log(value) // 1.11
Some useful error messages:
parse("(x-y)(x+y)", { x: 1, y: 2 });
// Error: Unexpected '(' at position 5.
// (x-y)(x+y)
// ▲
// ─────╯
Throws when it encounters an unspecified variable
parse("x^2 + y + 1" {x: 1e-1})
// Error: Unknown identifier 'y' at position 6.
//
// x^2 + y + 1
// ▲
// ──────╯