Formula Parser

Library provides a Parser class that evaluates excel and mathematical formulas.

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Install

A recommended way to install Formula Parser is through NPM using the following command:

$ npm install hot-formula-parser --save

Node.js:

var FormulaParser = require('hot-formula-parser').Parser;
var parser = new FormulaParser();

parser.parse('SUM(1, 6, 7)'); // It returns `Object {error: null, result: 14}`

Browser:

<script src="/node_modules/hot-formula-parser/dist/formula-parser.min.js"></script>
<script>
var parser = new formulaParser.Parser();

parser.parse('SUM(1, 6, 7)'); // It returns `Object {error: null, result: 14}`
</script>

Features

It supports:

• Any numbers, negative and positive as float or integer;
• Arithmetic operations like +, -, /, *, %, ^;
• Logical operations like AND(), OR(), NOT(), XOR();
• Comparison operations like =, >, >=, <, <=, <>;
• All JavaScript Math constants like PI(), E(), LN10(), LN2(), LOG10E(), LOG2E(), SQRT1_2(), SQRT2();
• String operations like & (concatenation eq. parser.parse('-(2&5)'); will return -25);
• All excel formulas defined in formula.js;
• Build-in variables like TRUE, FALSE, NULL
• Custom variables;
• Custom functions/formulas;
• Node and Browser environment.

API (methods)

var parser = new formulaParser.Parser();

.parse(expression)

Parses and evaluates provided expression. It always returns an object with result and error properties. result property always keep evaluated value. If error occurs error property will be set as:

• #ERROR! General error;
• #DIV/0! Divide by zero error;
• #NAME? Not recognised function name or variable name;
• #N/A Indicates that a value is not available to a formula;
• #NUM! Occurs when formula encounters an invalid number;
• #VALUE! Occurs when one of formula arguments is of the wrong type.

parser.parse('(1 + 5 + (5 * 10)) / 10'); // returns `Object {error: null, result: 5.6}`
parser.parse('SUM(MY_VAR)'); // returns `Object {error: "#NAME?", result: null}`
parser.parse('1;;1'); // returns `Object {error: "#ERROR!", result: null}`

.setVariable(name, value)

Set predefined variable name which can be visible while parsing formula expression.

parser.setVariable('MY_VARIABLE', 5);
parser.setVariable('fooBar', 10);

parser.parse('(1 + MY_VARIABLE + (5 * fooBar)) / fooBar'); // returns `5.6`

.getVariable(name)

Get variable name.

parser.setVariable('fooBar', 10);

parser.getVariable('fooBar'); // returns `10`

.setFunction(name, fn)

Set custom function which can be visible while parsing formula expression.

parser.setFunction('ADD_5', function(params) {
  return params[0] + 5;
});
parser.setFunction('GET_LETTER', function(params) {
  var string = params[0];
  var index = params[1] - 1;

  return string.charAt(index);
});

parser.parse('SUM(4, ADD_5(1))'); // returns `10`
parser.parse('GET_LETTER("Some string", 3)'); // returns `m`

.getFunction(name)

Get custom function.

parser.setFunction('ADD_5', function(params) {
  return params[0] + 5;
});

parser.getFunction('ADD_5')([1]); // returns `6`

.SUPPORTED_FORMULAS

List of all supported formulas function.

require('hot-formula-parser').SUPPORTED_FORMULAS; // An array of formula names

API (hooks)

'callVariable' (name, done)

Fired while retrieving variable. If variable was defined earlier using setVariable you can overwrite it by this hook.

parser.on('callVariable', function(name, done) {
  if (name === 'foo') {
    done(Math.PI / 2);
  }
});

parser.parse('SUM(SIN(foo), COS(foo))'); // returns `1`

'callFunction' (name, params, done)

Fired while calling function. If function was defined earlier using setFunction you can overwrite it's result by this hook. You can also use this to override result of build-in formulas.

parser.on('callFunction', function(name, params, done) {
  if (name === 'ADD_5') {
    done(params[0] + 5);
  }
});

parser.parse('ADD_5(3)'); // returns `8`

Want to help?

Please see CONTRIBUTING.md.

Changelog

To see the list of recent changes, see Releases section.

License

The MIT License (see the LICENSE file for the full text).

Contact

You can contact us at [email protected].