feelers

library1.5.1jsnpmunverified

FEELers is a string templating library built on top of DMN FEEL (Friendly Enough Expression Language), similar to Mustache or Handlebars. Version 1.5.1 (stable) is maintained under the bpmn-io organization. It provides a Lezer grammar/parser, a CodeMirror editor integration, and an interpreter using the feelin engine. Key differentiators: uses FEEL expressions for logic, supports conditionals (#if), loops (#loop), and variable inserts ({{}}).

productivity

npm install feelers

package ↗

INSTALL

IMPORT

SIG · FEELERS

feelers

productivityjavascriptv1.5.1

harness data pending

Install & Compatibility

Where this runs

No compatibility data collected yet for this library.

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

evaluate

✓ import { evaluate } from 'feelers'

✗ const evaluate = require('feelers')

ESM-only; default export not available

createEditor

✓ import { createEditor } from 'feelers'

✗ import createEditor from 'feelers'

Named export for CodeMirror editor

language

✓ import { language } from 'feelers'

✗ import { feelersLanguage } from 'feelers'

Lezer language definition object

Shows basic evaluate usage: plain strings, FEEL expressions, inserts, conditionals, and loops.

import { evaluate } from 'feelers'; const context = { user: 'Dave', hobbies: ['surfing', 'coding'] }; // Simple string console.log(evaluate('Hello World', context)); // 'Hello World' // FEEL expression console.log(evaluate('= 2 + 3', context)); // '5' // Template with inserts console.log(evaluate('Hello {{user}}', context)); // 'Hello Dave' // Conditional section console.log(evaluate('{{#if true}}Visible{{/if}}', context)); // 'Visible' // Loop console.log(evaluate('{{#loop hobbies}}- {{this}}\n{{/loop}}', context)); // '- surfing\n- coding\n'

Debug

Known issues

gotchaTemplate evaluation always returns string or Error. Do not expect objects or arrays.

fix

Use FEEL expression (=) for object conversion and stringify manually.

affects: >=1.0

gotchaLoop variable 'this' refers to current element; 'name' resolution only works if array element is object. For primitives use {{this}}.

fix

Use {{this}} for primitive values in loops.

affects: >=1.0

deprecatedThe 'createEditor' function may be deprecated in favor of new CodeMirror integration.

fix

Check documentation for latest editor setup.

affects: >=1.5

Errors

Common errors & fixes

Error: FEEL evaluation error: <error message>

Invalid FEEL expression syntax

fix

Ensure FEEL syntax is correct, e.g., check keywords, operators, and context variables.

TypeError: evaluate is not a function

CommonJS require instead of ESM import

fix

Use `import { evaluate } from 'feelers'` instead of `require('feelers')`.

Error: Template syntax error at line X

Mismatched or unclosed tags like {{#if}} without {{/if}}

fix

Ensure all opened sections are properly closed.

Upgrade

Version history

1.5.1latest on npm

Audit

Dependencies

feelinrequiredFEEL expression evaluation engine

lezerrequiredLezer parser for grammar

Agent activity

31 hits · last 30 days

node

OpenAI (training)

Resources

packagefeelers ↗