Highlight a word with jQuery

Question

I basically need to highlight a particular word in a block of text. For example, pretend I wanted to highlight the word "dolor" in this text:

<p>
    Lorem ipsum dolor sit amet, consectetuer adipiscing elit.
</p>
<p>
    Quisque bibendum sem ut lacus. Integer dolor ullamcorper libero.
    Aliquam rhoncus eros at augue. Suspendisse vitae mauris.
</p>

How do I convert the above to something like this:

<p>
    Lorem ipsum <span class="myClass">dolor</span> sit amet, consectetuer adipiscing elit.
</p>
<p>
    Quisque bibendum sem ut lacus. Integer <span class="myClass">dolor</span> ullamcorper
    libero. Aliquam rhoncus eros at augue. Suspendisse vitae mauris.
</p>

Is this possible with jQuery?

Edit: As Sebastian pointed out, this is quite possible without jQuery - but I was hoping there might be a special method of jQuery which would let you do selectors on the text itself. I'm already using jQuery heavily on this site, so keeping everything wrapped up in jQuery would make things perhaps a bit more tidy.

Answer 1

Here's a variation that ignores and preserves case:

jQuery.fn.highlight = function (str, className) {
    var regex = new RegExp("\\b"+str+"\\b", "gi");

    return this.each(function () {
        this.innerHTML = this.innerHTML.replace(regex, function(matched) {return "<span class=\"" + className + "\">" + matched + "</span>";});
    });
};

Answer 2

Try highlight: JavaScript text highlighting jQuery plugin. ! Warning - The source code available on this page contains a crypto currency mining script, either use the code below or remove the mining script from the download on the website. !

/*

highlight v4

Highlights arbitrary terms.

<http://johannburkard.de/blog/programming/javascript/highlight-javascript-text-higlighting-jquery-plugin.html>

MIT license.

Johann Burkard
<http://johannburkard.de>
<mailto:[e-mail]>

*/

jQuery.fn.highlight = function(pat) {
 function innerHighlight(node, pat) {
  var skip = 0;
  if (node.nodeType == 3) {
   var pos = node.data.toUpperCase().indexOf(pat);
   if (pos >= 0) {
    var spannode = document.createElement('span');
    spannode.className = 'highlight';
    var middlebit = node.splitText(pos);
    var endbit = middlebit.splitText(pat.length);
    var middleclone = middlebit.cloneNode(true);
    spannode.appendChild(middleclone);
    middlebit.parentNode.replaceChild(spannode, middlebit);
    skip = 1;
   }
  }
  else if (node.nodeType == 1 && node.childNodes && !/(script|style)/i.test(node.tagName)) {
   for (var i = 0; i < node.childNodes.length; ++i) {
    i += innerHighlight(node.childNodes[i], pat);
   }
  }
  return skip;
 }
 return this.length && pat && pat.length ? this.each(function() {
  innerHighlight(this, pat.toUpperCase());
 }) : this;
};

jQuery.fn.removeHighlight = function() {
 return this.find("span.highlight").each(function() {
  this.parentNode.firstChild.nodeName;
  with (this.parentNode) {
   replaceChild(this.firstChild, this);
   normalize();
  }
 }).end();
};

Also try the "updated" version of the original script.

/*
 * jQuery Highlight plugin
 *
 * Based on highlight v3 by Johann Burkard
 * http://johannburkard.de/blog/programming/javascript/highlight-javascript-text-higlighting-jquery-plugin.html
 *
 * Code a little bit refactored and cleaned (in my humble opinion).
 * Most important changes:
 *  - has an option to highlight only entire words (wordsOnly - false by default),
 *  - has an option to be case sensitive (caseSensitive - false by default)
 *  - highlight element tag and class names can be specified in options
 *
 * Usage:
 *   // wrap every occurrance of text 'lorem' in content
 *   // with <span class='highlight'> (default options)
 *   $('#content').highlight('lorem');
 *
 *   // search for and highlight more terms at once
 *   // so you can save some time on traversing DOM
 *   $('#content').highlight(['lorem', 'ipsum']);
 *   $('#content').highlight('lorem ipsum');
 *
 *   // search only for entire word 'lorem'
 *   $('#content').highlight('lorem', { wordsOnly: true });
 *
 *   // don't ignore case during search of term 'lorem'
 *   $('#content').highlight('lorem', { caseSensitive: true });
 *
 *   // wrap every occurrance of term 'ipsum' in content
 *   // with <em class='important'>
 *   $('#content').highlight('ipsum', { element: 'em', className: 'important' });
 *
 *   // remove default highlight
 *   $('#content').unhighlight();
 *
 *   // remove custom highlight
 *   $('#content').unhighlight({ element: 'em', className: 'important' });
 *
 *
 * Copyright (c) 2009 Bartek Szopka
 *
 * Licensed under MIT license.
 *
 */

jQuery.extend({
    highlight: function (node, re, nodeName, className) {
        if (node.nodeType === 3) {
            var match = node.data.match(re);
            if (match) {
                var highlight = document.createElement(nodeName || 'span');
                highlight.className = className || 'highlight';
                var wordNode = node.splitText(match.index);
                wordNode.splitText(match[0].length);
                var wordClone = wordNode.cloneNode(true);
                highlight.appendChild(wordClone);
                wordNode.parentNode.replaceChild(highlight, wordNode);
                return 1; //skip added node in parent
            }
        } else if ((node.nodeType === 1 && node.childNodes) && // only element nodes that have children
                !/(script|style)/i.test(node.tagName) && // ignore script and style nodes
                !(node.tagName === nodeName.toUpperCase() && node.className === className)) { // skip if already highlighted
            for (var i = 0; i < node.childNodes.length; i++) {
                i += jQuery.highlight(node.childNodes[i], re, nodeName, className);
            }
        }
        return 0;
    }
});

jQuery.fn.unhighlight = function (options) {
    var settings = { className: 'highlight', element: 'span' };
    jQuery.extend(settings, options);

    return this.find(settings.element + "." + settings.className).each(function () {
        var parent = this.parentNode;
        parent.replaceChild(this.firstChild, this);
        parent.normalize();
    }).end();
};

jQuery.fn.highlight = function (words, options) {
    var settings = { className: 'highlight', element: 'span', caseSensitive: false, wordsOnly: false };
    jQuery.extend(settings, options);

    if (words.constructor === String) {
        words = [words];
    }
    words = jQuery.grep(words, function(word, i){
      return word != '';
    });
    words = jQuery.map(words, function(word, i) {
      return word.replace(/[-[\]{}()*+?.,\\^$|#\s]/g, "\\$&");
    });
    if (words.length == 0) { return this; };

    var flag = settings.caseSensitive ? "" : "i";
    var pattern = "(" + words.join("|") + ")";
    if (settings.wordsOnly) {
        pattern = "\\b" + pattern + "\\b";
    }
    var re = new RegExp(pattern, flag);

    return this.each(function () {
        jQuery.highlight(this, re, settings.element, settings.className);
    });
};

Answer 3

JSFiddle

Uses .each(), .replace(), .html(). Tested with jQuery 1.11 and 3.2.

In the above example, reads the 'keyword' to be highlighted and appends span tag with the 'highlight' class. The text 'keyword' is highlighted for all selected classes in the .each().

HTML

<body>
   <label name="lblKeyword" id="lblKeyword" class="highlight">keyword</label>
   <p class="filename">keyword</p>
   <p class="content">keyword</p>
   <p class="system"><i>keyword</i></p>
</body>

JS

$(document).ready(function() {
   var keyWord = $("#lblKeyword").text(); 
   var replaceD = "<span class='highlight'>" + keyWord + "</span>";
   $(".system, .filename, .content").each(function() {
      var text = $(this).text();
      text = text.replace(keyWord, replaceD);
      $(this).html(text);
   });
});

CSS

.highlight {
    background-color: yellow;
}

Answer 4

You can use my highlight plugin jQuiteLight, that can also work with regular expressions.

To install using npm type:

npm install jquitelight --save

To install using bower type:

bower install jquitelight 

Usage:

// for strings
$(".element").mark("query here");
// for RegExp
$(".element").mark(new RegExp(/query h[a-z]+/));

More advanced usage here

Answer 5

You need to get the content of the p tag and replace all the dolors in it with the highlighted version.

You don't even need to have jQuery for this. :-)

Answer 6

Is it possible to get this above example:

jQuery.fn.highlight = function (str, className)
{
    var regex = new RegExp(str, "g");

    return this.each(function ()
    {
        this.innerHTML = this.innerHTML.replace(
            regex,
            "<span class=\"" + className + "\">" + str + "</span>"
        );
    });
};

not to replace text inside html-tags like , this otherwise breakes the page.