How to use jquery in ASP.​NET Core

Question

I created a ASP.NET core template and wrote a jquery script. When I look at the page I see that jquery is loaded into the page, but the script doesn’t run. I looked at the ASP.NET docs page and my layout.cshtml looks the same, so are there extra steps I must take to get jquery working? Home page

@{
    ViewData["Title"] = "Home Page";
}
<!-- Page Content-->
<div class="container">
    <div class="row">
        <form method="post" enctype="multipart/form-data">
            <input type="file" id="files" name="files" multiple />
            <input type="button" id="upload" value="Upload Selected Files" />
        </form>
    </div>
</div>
<script>
    $(document).ready(function () {
        alert("Test"); 
    });
</script>

Solution

@section scripts
{
    <script>
        $(document).ready(function() {
            alert("Test");
        });
    </script>
}

Solution 1

I suspect your jquery is loaded after the rest of the page content.

This means that you cannot reference jquery objects as the library has not been initialised yet.

Move the page script after jquery has loaded.

<script src="~/lib/jquery/dist/jquery.js"></script>
<script>
  $(document).ready(function () {
    alert("Test"); 
  });
</script>

For efficiency I recommend you do this in one of two ways:

---

OPTION 1

Use a master script file that loads after jquery.

<script src="~/lib/jquery/dist/jquery.js"></script>
<script src="~/js/master.js"></script>

---

OPTION 2

Use a placeholder template that will always load after jquery but can be initialised on individual pages.

Master _Layout Page

<script src="~/lib/jquery/dist/jquery.js""></script>
@RenderSection("Scripts", required: false)

Content Page

@section Scripts {
  <script>
    $(function () {
      alert("Test"); 
    });
  </script>
}

Solution 2

FOR CLARIFICATION

---

If you are referencing jQuery in your _Layout page.. double check to ensure that that reference is at the TOP of your _Layout page because if it is at the bottom, then every other page you have that use the _Layout and has jQuery, it will give you errors such as:

$ is undefined

because you are trying to use jQuery before it is ever defined!

Also, if your are referencing jQuery in your _Layout page then you do not need to reference it again in your pages that use your _Layout style

---

Make sure that you are loading the reference to jQuery before you start using <scripts>.

Your cshtml should work if you put the reference above your script as so:

<script src="~/Scripts/jquery-1.10.2.js"></script> // or whatever version you are using

// you do not need to use this reference if you are already referencing jQuery in your Layout page

<script>
    $(document).ready(function () {
        alert("Test"); 
    });
</script>

Solution 3

If you create a new .Net Core 2.2 - Web Application with Razor Pages and try to add a jQuery script in index.cshtml you will get the error Uncaught ReferenceError: $ is not defined. As already mentioned this is because jQuery is loaded after the rest of the page content.

Fix this by navigating to Pages\Shared\_Layout.cshtml and add the scripts section to the html head tag instead. Then it will work:

Example:

Move from below </footer>:

<environment include="Development">
    <script src="~/lib/jquery/dist/jquery.js"></script>
    <script src="~/lib/bootstrap/dist/js/bootstrap.bundle.js"></script>
</environment>
<environment exclude="Development">
    <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"
            asp-fallback-src="~/lib/jquery/dist/jquery.min.js"
            asp-fallback-test="window.jQuery"
            crossorigin="anonymous"
            integrity="sha256-FgpCb/KJQlLNfOu91ta32o/NMZxltwRo8QtmkMRdAu8=">
    </script>
    <script src="https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/js/bootstrap.bundle.min.js"
            asp-fallback-src="~/lib/bootstrap/dist/js/bootstrap.bundle.min.js"
            asp-fallback-test="window.jQuery && window.jQuery.fn && window.jQuery.fn.modal"
            crossorigin="anonymous"
            integrity="sha384-xrRywqdh3PHs8keKZN+8zzc5TX0GRTLCcmivcbNJWm2rs5C8PRhcEn3czEjhAO9o">
    </script>
</environment>
<script src="~/js/site.js" asp-append-version="true"></script>

@RenderSection("Scripts", required: false)

Into <head>, should look like this:

<head>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>@ViewData["Title"] - JiraApp.Clients.Web</title>

    <environment include="Development">
        <link rel="stylesheet" href="~/lib/bootstrap/dist/css/bootstrap.css" />
    </environment>
    <environment exclude="Development">
        <link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/css/bootstrap.min.css"
              asp-fallback-href="~/lib/bootstrap/dist/css/bootstrap.min.css"
              asp-fallback-test-class="sr-only" asp-fallback-test-property="position" asp-fallback-test-value="absolute"
              crossorigin="anonymous"
              integrity="sha384-ggOyR0iXCbMQv3Xipma34MD+dH/1fQ784/j6cY/iJTQUOhcWr7x9JvoRxT2MZw1T" />
    </environment>
    <link rel="stylesheet" href="~/css/site.css" />
    <environment include="Development">
        <script src="~/lib/jquery/dist/jquery.js"></script>
        <script src="~/lib/bootstrap/dist/js/bootstrap.bundle.js"></script>
    </environment>
    <environment exclude="Development">
        <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"
                asp-fallback-src="~/lib/jquery/dist/jquery.min.js"
                asp-fallback-test="window.jQuery"
                crossorigin="anonymous"
                integrity="sha256-FgpCb/KJQlLNfOu91ta32o/NMZxltwRo8QtmkMRdAu8=">
        </script>
        <script src="https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/js/bootstrap.bundle.min.js"
                asp-fallback-src="~/lib/bootstrap/dist/js/bootstrap.bundle.min.js"
                asp-fallback-test="window.jQuery && window.jQuery.fn && window.jQuery.fn.modal"
                crossorigin="anonymous"
                integrity="sha384-xrRywqdh3PHs8keKZN+8zzc5TX0GRTLCcmivcbNJWm2rs5C8PRhcEn3czEjhAO9o">
        </script>
    </environment>
    <script src="~/js/site.js" asp-append-version="true"></script>

    @RenderSection("Scripts", required: false)
</head>