@hapi/formula API v3.0.2

npm

npm install @hapi/formula@3.0.2

yarn

yarn add @hapi/formula@3.0.2

pnpm

pnpm add @hapi/formula@3.0.2

Example

const Formula = require('@hapi/formula');

const functions = {
  x: (value) => value + 10,
};

const constants = {
  Z: 100,
};

const reference = function (name) {
  return (context) => context[name];
};

const formula = new Formula.Parser('1 + a.b.c.2.4.x + [b] + x([y + 4] + Z)', {
  functions,
  constants,
  reference,
});

formula.evaluate({ 'a.b.c.2.4.x': 2, b: 3, 'y + 4': 5 }); // 1 + 2 + 3 + 5 + 10 + 100
formula.evaluate({ 'a.b.c.2.4.x': '2', b: 3, 'y + 4': '5' }); // '123510010'

Methods

new Formula.Parser(formula, [options])

Creates a new formula parser object where:

• formula - the formula string to parse.
• options - optional settings:
  • constants - a hash of key-value pairs used to convert constants to values.
  • tokenRx - a regular expression used to validate token variables.
  • reference - a variable resolver factory function with signature function(variable) which returns a function with signature function(context) returning the resolved variable.
  • functions - a hash of key-value pairs used to resolve formula functions.

parser.evaluate([context])

Evaluate the formula where:

• context - optional object with runtime formula context used to resolve variables.

Returns the string or number outcome of the resolved formula.