sformula 

Library for parsing / evaluating Salesforce formula in client-side (JavaScript).
Most of built-in functions in Salesforce are also ready-to-use and highly compatible with the original.

Install

``
$ npm i sformula
`

Usage

If the formula has no field reference, simply use parseSync() without any options.

`javascript
import { parseSync } from 'sformula';
// const { parseSync } = require('sformula');

const fml = parseSync('TODAY() + 1');
console.log(fml.evaluate()) // => (Tomorrow date will be shown)
`

Salesforce formula requires field types in the formula to parse and evaluate correctly.
For example, consider a formula like Field01__c + Field02__c.
The Field01__c and Field02__c fields might be both Number fields, or they might be Text fields.
Another possible case is Field01__c is Date/Datetime and Field02__c is Number.

So we need to add type annotation correctly when parsing the formula.
To compile the formula with field references, add inputTypes option to annotate field types.

`javascript
import { parseSync } from 'sformula';

const fml = parseSync('FirstName__c & " " & LastName__c', {
inputTypes: {
FirstName__c: { type: 'string' },
LastName__c: { type: 'string' },
},
})
const ret1 = fml.evaluate({ LastName__c: 'Due', FirstName__c: 'John' });
console.log(ret1); // 'John Due'
const ret2 = fml.evaluate({ FirstName__c: 'Jane' });
console.log(ret2); // 'Jane'
`

To add type annotation to the fields through relatinoship, write like below:

`javascript
import { parseSync } from 'sformula';

const fml = parseSync('Account__r.Name & " - " & Name', {
inputTypes: {
Account__r: {
type: 'object',
properties: {
Name: { type: 'string' },
},
},
Name: { type: 'string' },
},
})
const ret = fml.evaluate({ Account__r: { Name: 'Sunny, Inc.' }, Name: '10 Licenses' });
console.log(ret); // 'Sunny, Inc. - 10 Licenses'
`

The returnType option is used to cast the result type of the formula, which must be compatible with the calculated type from the formula.
Also, you can pass blankAsZero option when you want to regard the null value as zero (by default it is treated as blank).

`javascript
import { parseSync } from 'sformula';

const fml = parseSync('CreatedDate - Offset__c', {
inputTypes: {
CreatedDate: { type: 'datetime' },
Offset__c: { type: 'number', precision: 18, scale: 2 },
},
blankAsZero: true,
returnType: 'date'
})
const ret1 = fml.evaluate({ CreatedDate: '2018-01-01T10:00:00.000Z', Offset__c: 0.5 });
console.log(ret1); // '2018-12-31'
const ret2 = fml.evaluate({ CreatedDate: '2018-01-01T10:00:00.000Z' });
console.log(ret2); // '2018-01-01'
`

Are you tired to add type annotation by yourself ? OK, now it's time to tell the asynchronous parse() function and describer option.
In parse() you can pass an asynchronous function to describe the field types, and the parser will detect the types if it has entry in the described result. As a describer function you can simply use JSforce describe method, but not limited to.

`javascript
import { parse } from 'sformula';
import jsforce from 'jsforce';

const conn = new jsforce.Connection();
conn.login('username@domain.org', 'password123');

// ...

const fml = await parse('IF(CONTAINS(Owner.Title, "Engineer"), Number01__c + 2.5, Number02__c * 0.5)', {
sobject: 'CustomObject01__c', // root object name
describe: (sobject) => conn.describe(sobject), // (sobject: string) => Promise
blankAsZero: true,
returnType: 'number',
scale: 2
});
const ret1 = fml.evaluate({
Owner: { Id: '0057F000002wf0WQAQ', Name: 'John Due', Title: 'Software Engineer' },
Number02__c: 7,
});
console.log(ret1); // 2.5
const ret2 = fml.evaluate({
Owner: { Id: '00528000002J6BkAAK', Name: 'Jane Due', Title: 'Accountant' },
Number01__c: 11.5,
Number02__c: 7,
});
console.log(ret2); // 3.5

`

Supported Functions

$3

- [x] ADDMONTHS
- [x] DATE
- [x] DATEVALUE
- [x] DATETIMEVALUE
- [x] TIMEVALUE
- [x] YEAR
- [x] MONTH
- [x] DAY
- [x] WEEKDAY
- [x] HOUR
- [x] MINUTE
- [x] SECOND
- [x] MILLISECOND
- [x] TODAY
- [x] NOW
- [x] TIMENOW

$3

- [x] AND
- [x] OR
- [x] NOT
- [x] CASE
- [x] IF
- [x] ISNULL
- [x] ISBLANK
- [x] ISNUMBER
- [x] NULLVALUE
- [x] BLANKVALUE

$3

- [x] ABS
- [x] CEILING
- [x] FLOOR
- [x] ROUND
- [x] MCEILING
- [x] MFLOOR
- [x] EXP
- [x] LN
- [x] LOG
- [x] SQRT
- [x] MAX
- [x] MIN
- [x] MOD
- [ ] GEOLOCATION
- [ ] DISTANCE

$3

- [x] BEGINS
- [x] CONTAINS
- [x] INCLUDES
- [x] ISPICKVAL
- [x] FIND
- [x] LEFT
- [x] RIGHT
- [x] MID
- [x] LOWER
- [x] UPPER
- [x] LPAD
- [x] RPAD
- [x] SUBSTITUTE
- [x] TRIM
- [x] LEN
- [x] TEXT
- [x] VALUE
- [x] CASESAFEID
- [x] HYPERLINK
- [x] IMAGE
- [ ] BR
- [ ] ~~GETSESSIONID~~ (will not be supported)

$3

- [ ] CURRENCYRATE

Limitations

* Salesforce formula is "case-insensitive". For example, when IF(Field01__c > Field02__c, Owner.LastName, "-") is valid if(FIELD01__c > field02__c, owner.lastName, "-") is also a valid formula and yields same result. For implementation reason, sformula treats formula as "case-sensitive", which always requires functions to be written in UPPERCASE chars, fields to be written as same as which is defined in the API reference name.

* Global field references (fields under "$-prefixed" objects like $Label, $User`, ...) are not supported in built-in, but you can pass them as context if you like.