use-mathjs

A React hook built with mathjs for safely evaluating math expressions in your React apps.

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Features

- Evaluate math expressions (e.g. a + b, 2 * x + 3)
- Validate results and access error state
- Debounce evaluation for performance
- Flexible scope: supports plain objects and Map-like objects (including ES6 Map)

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Installation

``bash
npm install use-mathjs
`

> ⚠️ Requires react version 16.8.0 or above (Hooks support).

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Scope Type Support

The scope parameter for evaluate/evaluateSync supports:

- Plain objects: { a: 1, b: 2 }
- Map-like objects: Any object implementing get(key: string), set(key: string, value: unknown), has(key: string), and keys() (including ES6 Map)

This matches the flexibility described in the mathjs documentation.

Type definition:
`typescript
export interface MapLike {
get(key: string): unknown;
set(key: string, value: unknown): unknown;
has(key: string): boolean;
keys(): IterableIterator | string[];
}

export type ScopeType = Record | MapLike;
`

Examples:
`tsx
evaluate('a + b', { a: 1, b: 2 }) // plain object
evaluate('a + b', new Map([['a', 1], ['b', 2]])) // ES6 Map (Map-like)
evaluate('a + b', customMapLike) // any object with get/set/has/keys
`

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Usage Example

`tsx
import { useMath } from 'use-mathjs';

function Calculator() {
const { state, evaluate, evaluateSync, reset } = useMath({
initialResult: { result: 0, error: null, isValid: true },
errorMessageMap: (err) => Custom error: ${err instanceof Error ? err.message : String(err)},
debounceMs: 300,
});

return (


- initialResult — Initial state (default: { result: null, error: null, isValid: null })
- onEvaluated(result) — Callback after evaluation
- errorMessageMap(error) — Custom error message mapping
- debounceMs — Debounce evaluation in milliseconds

#### Return

- state — Current evaluation state { result, error, isValid }
- evaluate(expr, scope?) — Perform evaluation (debounced if set)
- evaluateSync(expr, scope?) — Synchronously evaluate expression
- reset()` — Reset state

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License

MIT