Wrap bootstrap modal in blazor with IJSRuntime

Question

Is it possible to get a reference to a Bootstrap 5 bootstrap.Modal via IJSRuntime and save a reference to that instance to later use it?

Example:

I can show a modal with this method:

await _jsRuntime.InvokeVoidAsync("eval", $"new bootstrap.Modal(document.getElementById('myId')).show()");

But I can't hide it the same way because I need to store a reference to the new bootstrap.Modal creation. How can I do this dynamically (I have a bootstrap modal component) without having to write javascript? Is there some way we can save variables and reference them later through the IJSRuntime?

Answer 1

After a lot of searching I found that eval is never the solution. I am not a JavaScript dev but I got this together:

BootstrapModal.razor

@inject IJSRuntime _jsRuntime;

<div class="modal fade" id="@Id" tabindex="-1">
    <div class="modal-dialog">
        <div class="modal-content">
            @ChildContent
        </div>
    </div>
</div>

@code {
    [Parameter]
    public string Id { get; set; }

    [Parameter]
    public RenderFragment ChildContent { get; set; }

    public dynamic Parameter { get; private set; }

    protected override void OnInitialized()
    {
        if (string.IsNullOrEmpty(Id))
        {
            Id = Guid.NewGuid().ToString();
        }
    }

    public async Task Show(dynamic parameter = null)
    {
        Parameter = parameter;

        await _jsRuntime.InvokeVoidAsync("BootstrapModal.ShowModal", Id);
    }

    public async Task Hide()
    {
        await _jsRuntime.InvokeVoidAsync("BootstrapModal.HideModal");
    }
}

BootstrapModalInterop.js

window.BootstrapModal = {};
window.BootstrapModal.OpenedModal = null;

window.BootstrapModal.ShowModal = (id) => {
    if (window.BootstrapModal.OpenedModal != null) {
        window.BootstrapModal.HideModal();
    }

    window.BootstrapModal.OpenedModal = new bootstrap.Modal(document.getElementById(id));
    window.BootstrapModal.OpenedModal.show();
}

window.BootstrapModal.HideModal = () => {
    if (window.BootstrapModal.OpenedModal == null) {
        return;
    }

    window.BootstrapModal.OpenedModal.hide();
    window.BootstrapModal.OpenedModal = null;
}

Make sure you reference the BootstrapModalInterop.js file from your hosts file.

You can now natively open and close the modal from blazor code.

Example usage:

...
<button class="btn btn-danger" @onclick="async () => await _deleteModal.Show(discountCode.Id)"><i class="fas fa-trash"></i></button>
...

<BootstrapModal @ref="_deleteModal">
    <div class="modal-header">
        <h5 class="modal-title">
            Delete Discount Code
        </h5>
    </div>
    <div class="modal-body">
        <p>
            Are you sure that you want to delete this discount code? This cannot be undone!
        </p>
    </div>
    <div class="modal-footer">
        <button @onclick="async () => await _deleteModal.Hide()" class="btn btn-secondary">Close</button>
        <button @onclick="async () => await Delete((int)_deleteModal.Parameter)" class="btn btn-outline-danger">Delete</button>
    </div>
</BootstrapModal>

@code 
{
  private BootstrapModal _deleteModal;
}

The parameter attribute is optional but I used it to parse the ID of the item I want to delete with it. Later I can get this ID using (int)_deleteModal.Parameter . I chose a dynamic type so I can parse in whatever.