Nervously Proposing Marriage


    0.24.2 • Public • Published


    olojs is a JavaScript library for managing olo-docs, which are text documents characterized as follows:

    • Documents are templates containing inline swan expressions enclosed between <% and %>.
    • Each document holds both data (the variables defined by the inline expressions) and narrative content (the text obtained by replacing each inline expression with its value)
    • Documents are contained in stores and identified by a path within their store. A store can be any repository (local, remote or a combination of both) implementing the Store interface.
    • Each document can import and use the narrative content and data held by any other documents of the same store.


    Let's assume that a store contains the following document at /people/mary:

    <% name: "Mary" %> is <% age: 35 %> years old.

    Once evaluated, this document renders to Mary is 35 years old and returns the namespace {name: "Mary", age: 35}.

    Let's now assume that the same store contains also the following document, mapped to the path /people/bob:

    <% wife = import "./mary" %>
    <% name: "Bob" %> is <% age: 40 %> years old and he is married to <% %>,
    who is <% wife.age %> years old. Therefore <% name %> is <% age - wife.age %>
    years older than <% %>.

    Notice that /people/bob imports /people/mary and uses its content. Once evaluated it renders to:

    Bob is 40 years old and he is married to Mary, who is 35 years old.
    Therefore Bob is 5 years older than Mary.

    The /people/bob document returns the following namespace:

        name: "Bob",
        age: 40,
        wife: {
            name: "Mary",
            age: 35

    The above example gives an idea of how documents work, but to really appreciate this library, you need to consider a) that swan is a powerful expression language which, for example, can define functions and therefore parametric chunks of text and b) that stores can be shared over the internet generating a distributed network of documents.

    Getting started

    Install olojs via npm

    npm install @onlabsorg/olojs --save

    Import olojs and connect to a store:

    olo = require('@onlabsorg/olojs');
    store = new olo.FileStore('/home/my-olodocs-store');

    In this example a file-system-based store is used, but a store can be any object implementing the Store interface. olojs comes with a number of predefined stores, namely MemoryStore, FileStore, HTTPStore, BrowserStore and a multi-store Router.

    Load, evaluate and render a document:

    docPath = '/path/to/doc';
    source = await;                 // fetch the document source
    evaluate = store.parse(source);                     // compile the document
    context = store.createContext(docPath, {pi:3.14});  // create an evaluation context
    {data, text} = await evaluate(context);             // evaluate the document

    Serve the store via HTTP:

    server = olo.HTTPServer.create(store);

    Interface to your store via HTTP:

    remoteStore = new olo.HTTPStore('http://localhost:8010');
    source = await'/path/to/doc');

    olojs works also in the browser, although it has been tested only on Chrome. In order to use the olojs library in the browser, you should require the module @onlabsorg/olojs/browser. The only difference between the NodeJS version and the browser version is that the latter doesn't contain the FileStore class and the HTTPServer object, but it contains the BrowserStore instead.

    Learn more


    • npm run node-test tests the library in NodeJS
    • npm run browser-test tests the library in the browser



    Related projects

    • stilo is a command-line interface written in NodeJS that allows you to create and mange local olojs document repositories.
    • olowiki is a HTTP client and stilo plugin for editing and rendering olojs documents in the browser


    npm i @onlabsorg/olojs

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