I'm having trouble wrapping my head around this jQuery script

Question

I'm having trouble wrapping my head around this jQuery script

I'm in the process of designing a website that will feature two distinct themes: green and blue. By default, the color scheme is set to green, but users will have the option to switch to a blue theme by clicking on a button.

After doing some research on various resources, I came across a code snippet that seems like it could help achieve this functionality:

function updateStyleSheet(filename) {
    newstylesheet = "Content/css/" + filename + ".css";
    if ($("#dynamic_css").length == 0) {
        $("head").append("<link>")
        css = $("head").children(":last");
        css.attr({
            id: "dynamic_css",
            rel: "stylesheet",
            type: "text/css",
            href: newstylesheet
        });
    } else {
        $("#dynamic_css").attr("href", newstylesheet);
    }
}

If my understanding is correct, this script should replace the current stylesheet with a new one when called upon. My website has two stylesheets named stylegreen.css and styleblue.css. Where in the provided code should I make modifications for it to work seamlessly? Additionally, do I need to include this script within the HTML file and how should I create the button to trigger the theme change?

javascript jquery html css

Answer 1

Answer №1

This function is designed to dynamically add a HTML link tag to the header section of a webpage when it is activated. To implement it successfully, you will need to follow these steps:

1 - Ensure that jQuery is included by importing the jQuery library

<script src="http://code.jquery.com/jquery-1.11.2.min.js"></script>

2 - Adjust the file path for your CSS file accordingly

newstylesheet = "your/path/" + filename + ".css";

3 - Use the function by specifying the name of the desired CSS file

updateStyleSheet("styleblue"); // attach styleblue.css to your page
updateStyleSheet("stylegreen"); // attach styleblue.css to your page

Here is a complete example:

<html>
<head>
   <script src="http://code.jquery.com/jquery-1.11.2.min.js"></script>
</head>
<body>
    <select id="styleSelect">
        <option value="styleblue">Blue</option>
        <option value="stylegreen">Green</option>
    </select>

    <script>
      function updateStyleSheet(filename) {
        newstylesheet = "path/to/css/" + filename + ".css";
        if ($("#dynamic_css").length == 0) {
          $("head").append("<link>")
          css = $("head").children(":last");
          css.attr({
            id: "dynamic_css",
            rel: "stylesheet",
            type: "text/css",
            href: newstylesheet
          });
        } else {
          $("#dynamic_css").attr("href", newstylesheet);
        }
      }

      // A bonus feature: This function automatically triggers the updateStyleSheet function
      // with the selected value from the dropdown menu as an argument when the selection changes
      $("#styleSelect").change(function() {
           updateStyleSheet($(this).val());
      });
    </script>
</body>

Answer 2

This function is designed to dynamically add a HTML link tag to the header section of a webpage when it is activated. To implement it successfully, you will need to follow these steps:

1 - Ensure that jQuery is included by importing the jQuery library

<script src="http://code.jquery.com/jquery-1.11.2.min.js"></script>

2 - Adjust the file path for your CSS file accordingly

newstylesheet = "your/path/" + filename + ".css";

3 - Use the function by specifying the name of the desired CSS file

updateStyleSheet("styleblue"); // attach styleblue.css to your page
updateStyleSheet("stylegreen"); // attach styleblue.css to your page

Here is a complete example:

<html>
<head>
   <script src="http://code.jquery.com/jquery-1.11.2.min.js"></script>
</head>
<body>
    <select id="styleSelect">
        <option value="styleblue">Blue</option>
        <option value="stylegreen">Green</option>
    </select>

    <script>
      function updateStyleSheet(filename) {
        newstylesheet = "path/to/css/" + filename + ".css";
        if ($("#dynamic_css").length == 0) {
          $("head").append("<link>")
          css = $("head").children(":last");
          css.attr({
            id: "dynamic_css",
            rel: "stylesheet",
            type: "text/css",
            href: newstylesheet
          });
        } else {
          $("#dynamic_css").attr("href", newstylesheet);
        }
      }

      // A bonus feature: This function automatically triggers the updateStyleSheet function
      // with the selected value from the dropdown menu as an argument when the selection changes
      $("#styleSelect").change(function() {
           updateStyleSheet($(this).val());
      });
    </script>
</body>

Answer 3

Answer №2

If you find yourself with only 2 stylesheets, there is a good chance you can streamline your process.

It may be as simple as giving the default link tag an ID by hardcoding it if necessary. If hardcoding is not ideal, there are alternative methods to target the correct link tag

<link id="site_theme" href="path/to/css/styles_green.css" data-color="green">

In JavaScript:

/* Attach a click function to a button */
$('#someButtonId').click(function () {
    /* Define the link tag as a jQuery object */
    var $link = $('#site_theme'),
        /* Retrieve current color stored in data attribute */
        currColor = $link.data('color'),
        /* Set new color*/
        newColor = currColor === 'green' ? 'blue' : 'green';
    /* Update the href attribute for the new theme color */
    $link.attr('href', function (_, currHref) {
        return currHref.replace(currColor, newColor);
        /* Update the data attribute with the new color */
    }).data('color', newColor);
});

This method assumes that the colors are part of the filenames of the CSS files.

Clicking the button multiple times will switch between the themes back and forth

Answer 4

If you find yourself with only 2 stylesheets, there is a good chance you can streamline your process.

It may be as simple as giving the default link tag an ID by hardcoding it if necessary. If hardcoding is not ideal, there are alternative methods to target the correct link tag

<link id="site_theme" href="path/to/css/styles_green.css" data-color="green">

In JavaScript:

/* Attach a click function to a button */
$('#someButtonId').click(function () {
    /* Define the link tag as a jQuery object */
    var $link = $('#site_theme'),
        /* Retrieve current color stored in data attribute */
        currColor = $link.data('color'),
        /* Set new color*/
        newColor = currColor === 'green' ? 'blue' : 'green';
    /* Update the href attribute for the new theme color */
    $link.attr('href', function (_, currHref) {
        return currHref.replace(currColor, newColor);
        /* Update the data attribute with the new color */
    }).data('color', newColor);
});

This method assumes that the colors are part of the filenames of the CSS files.

Clicking the button multiple times will switch between the themes back and forth

I'm having trouble wrapping my head around this jQuery script

Answer №1

Answer №2

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