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Basic lens structure

Functions interface​

A Lens is a JavaScript program that defines how to transform an ePI document. The basic structure of a Lens includes:

Required and Optional Functions​

  • enhance function (mandatory): This function takes the original ePI content as input and returns the transformed content. It is where you define how to modify the ePI.
  • explanation function (optional): This function provides a human-readable explanation of the changes made by the enhance function. It can be useful for users to understand what modifications were applied.

Example Structure​

Here is a simple example of a Lens structure:

/*
  Input data
    These variables are automatically populated by the lens execution environment.
*/
// ePI data
let epiData = epi;
// IPS data
let ipsData = ips;
// PV data (for future use)
let pvData = pv;
// Original HTML content to be transformed
let htmlData = html;


/* 
    Enhance function: Transforms the original content to highlight specific sections.
    Input: htmlData (string) - The original text content.
           ipsData (object) - The IPS resource data.
           pvData (object) - The PV resource data.
           epiData (object) - The ePI resource data.
    Output: transformedContent (string) - The modified text content with highlights.
*/
function enhance() { 
    // Your transformation logic here
    transformedContent = htmlData; // Placeholder
    return transformedContent;
}

/* 
    Explanation function: Provides an explanation for the lens's behavior.
    Output: explanationText (string) - A textual explanation.
*/
function explanation() {
    // Your explanation logic here
    var explanationText = "This lens highlights relevant sections for your health condition beacuse...";
    return explanationText;
}

return {
    enhance: enhance,
    explanation: explanation
};

Implementation strategies​

When implementing a Lens, consider the following strategies to ensure it is effective and efficient:

Use of Regular Expressions​

Regular expressions are powerful tools for pattern matching and text manipulation. They can be used to identify specific sections of the ePI that need to be modified.

Example Use Case

You can use regular expressions to find all instances of a particular term or phrase and replace them with a highlighted version.

DOM Manipulation​

If the ePI content is structured as HTML, you can use DOM manipulation techniques to traverse and modify the document. This allows for more precise control over the elements being changed, such as adding classes or attributes to specific tags.

Precision Control

DOM manipulation provides fine-grained control over HTML elements, making it ideal for targeted modifications.

Performance Considerations​

Efficiency Requirements

Lenses should be designed to run efficiently, especially if they are executed on client devices with limited resources. Avoid complex computations and ensure that the enhance function executes quickly.

Offload Heavy Tasks

Consider using pre-processors for any heavy computational tasks that can be done before the Lens is applied.

Testing and Validation​

Coming Soon

Testing and validation guidelines will be added in a future version of this documentation.