@kelta/formula

@kelta/formula evaluates the same expression language the server uses, so a client can validate before it submits or compute a formula field locally. Parity with the Java engine is covered by shared tests.

import { FormulaEvaluator } from '@kelta/formula';

const evaluator = new FormulaEvaluator();
evaluator.evaluate('amount * (1 + tax_rate)', { amount: 100, tax_rate: 0.23 });      // 123
evaluator.evaluate('ISBLANK(email) OR NOT CONTAINS(email, "@")', { email: 'x' });   // true → a rule would reject

API#

Export	Purpose
FormulaEvaluator (evaluate(expr, fields), registerFunction(fn))	evaluate against a field map; add custom functions
FormulaParser	parse to an AST
evaluateAst, extractFieldRefs	evaluate a parsed AST; list the fields an expression reads (for dependency tracking)
toDouble, toBoolean	coercion helpers matching the server
FormulaException	parse/evaluation errors

Grammar and built-ins#

Identical to the server: field references, string/number/boolean literals, + - * /, comparisons (= == != <> < <= > >=), AND/&&, OR/||, NOT/!, unary minus, parentheses, and the 21 built-in functions TODAY NOW ISBLANK BLANKVALUE IF AND OR NOT LEN CONTAINS UPPER LOWER TRIM TEXT VALUE ROUND ABS MAX MIN REGEX DATEDIFF. Details: Formula and roll-up fields.

Where it runs#

• The app evaluates enforceOnClient validation rules before submitting (the server always re-evaluates).
• Page-builder {{= … }} expressions and computed variables.
• Your own forms, via the evaluator above.

A custom function registered client-side has no server counterpart; keep client-only functions to display logic.

Full API reference#

Every export of @kelta/formula with its TypeScript signature and doc summary, generated from the package source: @kelta/formula — API Reference.