Content aware document Highlighter

What is document highlighter?

Add highlight to a raw / HTML document for the specified query. Handle unicode, stop-words and punctuation. Generate HTML-compliant highlights, even for complex markup.

Samples

Plain text

Simple case

The following text :

The index analysis module acts as a configurable registry of Analyzers that can be used in order to both break indexed (analyzed) fields when a document is indexed and process query strings. It maps to the Lucene Analyzer.

When highlighted for the query The index analysis string will become:

The index analysis module acts as a configurable registry of Analyzers that can be used in order to both break indexed (analyzed) fields when a document is indexed and process query strings. It maps to the Lucene Analyzer.

Note generated markup is minimal (one item per match, and not one item per word).

Stopwords

Document highlighter handles stopwords and punctuation according to the language specified. For instance, the following text:

Install this library, and start using it.

When highlighted for the query install library will become:

Install this library, and start using it.

HTML

This also works for HTML documents, e.g. :

This document contains italics and stuff.

When highlighted for the query it contains some italic empty will become:

This document contains italics and stuff.

Document highlighter maintains original markup and add wrapping tags as needed.

Usage

Highlight plain text documents

var highlighter = require('document-highlighter');

var hl = highlighter.text(
    'In JavaScript, you can define a callback handler in regex string replace operations',
    'callback handler in operations'
);

console.log(hl.text);
// "In JavaScript, you can define a <strong>callback handler in</strong> regex string replace <strong>operations</strong>"

console.log(hl.indices);
// [
//   { startIndex: 32, endIndex: 51, content: 'callback handler in' },
//   { startIndex: 73, endIndex: 83, content: 'operations' }
// ]

Highlight HTML documents

var highlighter = require('document-highlighter');

var hl = highlighter.html(
    '<em>Eat drink and be merry</em> for tomorrow we die',
    'merry for tomorrow'
);

console.log(hl.html);
// <em>Eat drink and be <strong>merry</strong></em><strong class="secondary"> for tomorrow</strong> we die

console.log(hl.text);
// Eat drink and be <strong>merry for tomorrow</strong> we die

Customize highlight markup

var highlighter = require('document-highlighter');

var hl = highlighter.text(
    'In JavaScript, you can define a callback handler in regex string replace operations',
    'callback handler in operations',
    {
        before: '<span class="hlt">',
        after: '</span>',
    }
);

console.log(hl.text);
// "In JavaScript, you can define a <span class="hlt">callback handler in</span> regex string replace <span class="hlt">operations</span>"

Note: in HTML mode, your highlight may be split up in multiple items in order to keep your existing markup (block level elements stop inline highlighting). The default is to add a .secondary class; but you can override this using the beforeSecond key in the option.

In some case, you may want to customize highlighting for all calls to the highlighter. You can use defaultOptions parameter. Note you cannot directly override this with a new object; you need to update the keys one by one.

var highlighter = require('document-highlighter');
highlighter.defaultOptions.before = '<span class="hlt">';
highlighter.defaultOptions.after = '</span>';

var hl = highlighter.text(
    'In JavaScript, you can define a callback handler in regex string replace operations',
    'callback handler in operations'
);

console.log(hl.text);
// "In JavaScript, you can define a <span class="hlt">callback handler in</span> regex string replace <span class="hlt">operations</span>"