feelers

A templating solution built on top of DMN FEEL. Like mustache / handlebars but with FEEL.

Usage

import { evaluate } from 'feelers';

A simple string will always be returned as-is.

evaluate("My simple string");
// "My simple string"

If your string is prefixed with an =, it will be evaluated as a single FEEL expression wrapped in a string conversion function.

const context = { secondNumber: 12 };
evaluate("= 2 + secondNumber", context);
// "14"

Finally, if your string features feelers language features, the templating engine takes over.

const context = { user: "Dave" };
evaluate("I'm sorry {{user}}, I'm afraid I can't do that.", context);
// I'm sorry Dave, I'm afraid I can't do that.

Language features

Inserts

The simplest feature of feelers is inserting FEEL evaluations within your text.

const context = { user: "Dave", age: 24, hobbies: [ "surfing", "coding" ] };

evaluate(`Hey there {{user}}, welcome. {{if age >= 18 then "Have a beer!" else "Here's some apple juice."}}`, context);
// Hey there Dave. Have a beer!

Conditional sections

const context = { users: [ "Bob", "Dave" ] };
evaluate(`{{#if count(users) > 1}}There are multiple users{{/if}}`, context);
// There are multiple users

Loops

const context = { user: "Dave", hobbies: [ "surfing", "coding" ] };
evaluate(`{{user}}'s hobbies:\n{{#loop hobbies}}\n- {{this}}\n{{/loop}}`, context);
// Dave's hobbies:
// - surfing
// - coding

Build and run

Prepare the project by installing all dependencies:

npm install

Then, depending on your use-case you may run any of the following commands:

# build the library and run all tests
npm run all

# run the development setup
npm run dev

Related

• feelers - FEELers monorepo
• @bpmn-io/lezer-feelers - FEELers parser definition
• @bpmn-io/lang-feelers - FEELers language support for CodeMirror 6
• @bpmn-io/feelers-lint - FEELers linting support for CodeMirror 6
• @bpmn-io/feelers-editor - FEELers editor component
• lezer-feel - FEEL language definition for the Lezer parser system

License

MIT