I have this in an private async Task method

await JsRuntime.InvokeVoidAsync("Test");

and is working with this :

async function Test() {
    return await new Promise((resolve) => {
        iframe = document.createElement('iframe');
        iframe.style.display = 'none';
        iframe.src = "https://localhost/order/create";
        document.body.appendChild(iframe);

        iframe.onload = function () {
            setTimeout(function () {
                iframe.contentWindow.print();
            }, 1);
        };

        iframe.contentWindow.onafterprint = function () {
            resolve();
        }
    })
}

but when i use a blob my promise don’t return anything and i don’t know why :

async function BlazorDownloadFile(content) {
    return await new Promise((resolve) => {
        var blob = new Blob([content], { type: 'application/pdf' }); 
        var blobURL = URL.createObjectURL(blob);

        iframe = document.createElement('iframe'); 
        iframe.style.display = 'none';
        iframe.src = blobURL;
        document.body.appendChild(iframe);

        iframe.onload = function () {
            setTimeout(function () {
                iframe.contentWindow.print();
            }, 1);
        };

        iframe.contentWindow.onafterprint = function () {
            resolve(true);
        }
    })
}

Can someone help me…