How to use Bootstrap Carousel in Blazor

Question

newbie in Blazor. Need to try out how to use BS carousel in Blazor.

I used below code in the Default Blazor app. But it does not work. What I need to do?

Thanks

I added this line in the Index.html

<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.4.0/jquery.min.js"></script>
In the Counter page. I added the following:

<div class="carousel-inner">

  <div class="item active">
    <img src="la.jpg" alt="Los Angeles" style="width:100%;">
    <div class="carousel-caption">
      <h3>Los Angeles</h3>
      <p>LA is always so much fun!</p>
    </div>
  </div>

  <div class="item">
    <img src="chicago.jpg" alt="Chicago" style="width:100%;">
    <div class="carousel-caption">
      <h3>Chicago</h3>
      <p>Thank you, Chicago!</p>
    </div>
  </div>

  <div class="item">
    <img src="ny.jpg" alt="New York" style="width:100%;">
    <div class="carousel-caption">
      <h3>New York</h3>
      <p>We love the Big Apple!</p>
    </div>
  </div>

</div>


<a class="left carousel-control" href="#myCarousel" data-slide="prev">
  <span class="glyphicon glyphicon-chevron-left"></span>
  <span class="sr-only">Previous</span>
</a>
<a class="right carousel-control" href="#myCarousel" data-slide="next">
  <span class="glyphicon glyphicon-chevron-right"></span>
  <span class="sr-only">Next</span>
</a>

< /div >

-- Update: Index.html

<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width" />
    <title>BlazorCarouselTest</title>
    <base href="/" />
    <link href="css/bootstrap/bootstrap.min.css" rel="stylesheet" />
    <link href="css/site.css" rel="stylesheet" />
    <script src="css/bootstrap/jquery-3.4.0.min.js" type="text/javascript"></script>
</head>
<body>
    <app>Loading...</app>

    <script src="_framework/blazor.webassembly.js"></script>
</body>
</html &gt;

No Err msg. It showed all the 3 images vertically. It suppose to show a horizontal scroll image by image. I had downloaed the jquery-3.4.0.js and place it in the same folder as bootstrap. — MilkBottle
Did your Blazor project include all the required JS for carousel? see the bootstrap quickstart page - specifically the JS section. Maybe show us the head section of your index.html? — Mister Magoo

dani herrera dani herrera · Accepted Answer · 2019-06-11T16:21:30

Carousel needs a bit of javascript code, it needs to be configured on page load, but, into a blazor page, nobody calls the initialization for the component. The good news is that you can do it by code.

Three easy steps:

1.- Create and include javascript on blazor (you can copy paste this code at bottom of your index.html page )

<script>
window.initializeCarousel = () =>
{
    $('#carouselExampleIndicators').carousel({interval: 2000});

    //see step 2 to understand these news id's:
    $('#carouselExampleIndicators-prev').click ( 
            () => $('#carouselExampleIndicators').carousel('prev') );
    $('#carouselExampleIndicators-next').click ( 
            () => $('#carouselExampleIndicators').carousel('next') );

}
</script>

2.- Change a bit the carousel's html ( remove href from carousel-control-prev divs. Add an id for prev and next controls ):

<div id="carouselExampleIndicators" 
     class="carousel slide" data-ride="carousel">
  <ol class="carousel-indicators">
    <li data-target="#carouselExampleIndicators" data-slide-to="0" class="active"></li>
    <li data-target="#carouselExampleIndicators" data-slide-to="1"></li>
  </ol>
  <div class="carousel-inner">
    <div class="carousel-item  active">
      <img class="d-block w-50" src="..." alt="Pepa Pig">
    </div>
    <div class="carousel-item">
      <img class="d-block w-50" src="..." alt="Sponge Bob">
    </div>
  </div>
  <a id="carouselExampleIndicators-prev" 
     class="carousel-control-prev" role="button" data-slide="prev">
    <span class="carousel-control-prev-icon" aria-hidden="true"></span>
    <span class="sr-only">Previous</span>
  </a>
  <a id="carouselExampleIndicators-next" 
     class="carousel-control-next" role="button" data-slide="next">
    <span class="carousel-control-next-icon" aria-hidden="true"></span>
    <span class="sr-only">Next</span>
  </a>
</div>

3.- Call the previous code after first render:

@page "/counter"
@inject IJSRuntime JsRuntime;
...

@functions {
    int currentCount = 0;
    bool firstRender = true; 
    ...
    protected async override Task OnAfterRenderAsync()
    {
      if (firstRender) 
      {
        await JsRuntime.InvokeAsync<object>("initializeCarousel");
        firstRender=false;
      }
    }

That's all:

Let us know if you your carousel is moving now!

Edited

Remember to include all js needed to run bootstrap carousel on index.html:

<body>
    <app>Loading...</app>

    <script
    src="https://code.jquery.com/jquery-3.4.1.min.js"
    integrity="sha256-CSXorXvZcTkaix6Yvo6HppcZGetbYMGWSFlBw8HfCJo="
    crossorigin="anonymous"></script>    
    <script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.7/umd/popper.min.js" 
    integrity="sha384-UO2eT0CpHqdSJQ6hJty5KVphtPhzWj9WO1clHTMGa3JDZwrnQq4sF86dIHNDz0W1" 
    crossorigin="anonymous"></script>
    <script src="https://stackpath.bootstrapcdn.com/bootstrap/4.3.1/js/bootstrap.min.js" 
    integrity="sha384-JjSmVgyd0p3pXB1rRibZUAYoIIy6OrQ6VrjIEaFf/nJGzIxFDsf4x0xIM+B07jRM" 
    crossorigin="anonymous"></script>    
    <script src="_framework/blazor.webassembly.js"></script>

    <script>
    window.initializeCarousel = () =>
    {
        $('#carouselExampleIndicators').carousel({interval: 2000})
        $('#carouselExampleIndicators-prev').click ( 
            () => $('#carouselExampleIndicators').carousel('prev') );
        $('#carouselExampleIndicators-next').click ( 
            () => $('#carouselExampleIndicators').carousel('next') );
    }
    </script>
</body>

How to use Bootstrap Carousel in Blazor

2 Answers