How can I highlight text using jQuery?

Highlighting Text with jQuery

Problem Description:

You want to highlight a particular word within a given block of text using jQuery.

Solution:

To highlight a word using jQuery, you can utilize plugins such as highlight or the updated version of the original script provided below:

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();
};

Alternative Approach:

If you prefer a more recent and feature-rich solution, consider the following plugin:

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, "\$&amp;&");
  });
  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);
  });
};

This plugin provides additional features such as the ability to specify custom tag names and class names for the highlighted elements, search for multiple terms simultaneously, and perform case-sensitive searches. It also includes a method to remove existing highlighting.

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