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Learning jQuery Third Edition by Karl Swedberg, Jonathan Chaffer

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Plain JavaScript vs. jQuery

Even a task as simple as this can be complicated without jQuery at our disposal. In plain JavaScript, we could add the highlighted class as shown in the following code snippet:

window.onload = function() {
  var divs = document.getElementsByTagName('div');
  for (var i = 0; i < divs.length; i++) {
    if (hasClass(divs[i], 'poem-stanza')&& !hasClass(divs[i], 'highlight')) {divs[i].className += ' highlight';
    }
  }

  function hasClass( elem, cls ) {
    var reClass = new RegExp(' ' + cls + ' ');
    return reClass.test(' ' + elem.className + ' ');
  }
};

Listing 1.3

Despite its length, this solution does not handle many of the situations that jQuery takes care of for us in Listing 1.2, such as the following:

  • Properly respecting other window.onload ...

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