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Modules overview

What are modules?

As stated in the scripting overview, the main.jr file is where the text intelligence engine expects to find a script that allows extending the document analysis pipeline. When executing the pipeline, the engine triggers the event handlers defined in that file and those event handlers can use other functions and variables defined within the same file.

It is also possible to use code written in other files given they have the .jr extension and their code is adequately structured. These additional files are called modules.

A module is roughly comparable to a class of objects.
Module objects are instantiated with this syntax:

var modVar = require(modulePath);

where modulePath is the path of the module's .jr file with respect to the project folder and without the extension.
Variable modVar becomes an instance of the module.
For example, this statement:

var sphere1 = require("modules/sphere");

makes variable sphere1 an instance of module sphere which corresponds to the sphere.jr file that has to be found in a sub-folder named modules inside the project folder.

Note

The use of require() is not limited to the main.jr file, it can also be used in a module to instantiate other modules.

Methods and properties

By default, functions, variables and constants defined within a module have a local scope, which means they are not accessible to code outside the module.
The functions, variables and constants that you want to make accessible from outside the module must be "exported" and this is achieved by assigning them to as many properties of the predefined exports object.
In this way, functions become methods while variables and constants become properties of objects instantiated with the require() function.

To illustrate this, let's use the example of a geometric object, the sphere.
What we want is a module whose instances represent spheres, with a "create" method working as a class constructor having the radius of the sphere as its only parameter.
We want every sphere to expose the values of its surface and its volume through object's properties.
The module file could be called sphere.jr, be located in the modules sub-folder of the project and have these contents:

var localSurface;
var localVolume;

function surfaceFunction(radius) {
    return 4 * Math.PI * Math.pow(radius, 2);
}

function volumeFunction(radius) {
    return 4 / 3 * Math.PI * Math.pow(radius, 3);
}

function createFunction(radius) {
    localSurface = surfaceFunction(radius);
    localVolume = volumeFunction(radius);

    exports.surface = localSurface;
    exports.volume = localVolume;
}

exports.create = createFunction;

The createFunction function "creates" a sphere with the given radius by computing its surface and its volume. The results of these computations are first stored in two local variables that are then exposed as module—and therefore, object—properties using the exports object. Eventually the createFunction function is exposed as a module method.
export.surface, exports.volume and exports.create are properties of the exports object defined on the fly. The first two expose internal variables localSurface and localVolume as public properties surface and volume, while the third exposes function createFunction as the create() method.
Neither the surfaceFunction and the volumeFunction functions nor the localSurface and the localVolume variables are visible from outside.

The module can be used like this inside main.jr:

var sphere1 = require("modules/sphere");

sphere1.create(7.5);

CONSOLE.log('The surface of a sphere with a radius of 7.5 is ' + sphere1.surface + ' and the volume is ' + sphere1.volume);

As stated above, also constants can become public properties of a module using this syntax:

exports.property = constant

Studio ready-to-use modules

You are free to write custom modules, but first consider the following modules, which are predefined in Studio so they can be copied and used in any project:

Module Functionalities
regexcleaner Advanced find-and-replace operations based on regular expressions
dompost Post-processing of output categories' labels
normalizepost Normalization of extracted values
mergepost Merger of extraction records
moment Parsing, validation and manipulation of dates and times
jmespath Parsing and navigation of JSON objects based on the JMESPath query language
jsonpath Parsing and navigation of JSON objects based on the JSONPath query language
jsonPlug Free style manipulation of results
tagHierarchy Hierarchy between strong and weak tags

These modules are the transposition of open source projects:

and expose the same functionalities of their GitHub counterparts. The other modules are described in detail in the following articles in this section.

You can manage your modules with the JR Modules Manager.