我们可以使用中间件来实现它，我们应该让这个npm脚本只运行一次。下面是我的示例中间件。

NpmMiddleware.cs

public class NpmMiddleware
{
    private static bool _npmScriptStarted = false;
    private readonly RequestDelegate _next;
    private readonly string _sourcePath;
    private readonly string _npmScript;

    public NpmMiddleware(RequestDelegate next, string sourcePath, string npmScript)
    {
        _next = next;
        _sourcePath = sourcePath;
        _npmScript = npmScript;
    }

    public async Task InvokeAsync(HttpContext context)
    {
        if (!_npmScriptStarted)
        {
            var isDevelopment = string.Equals(Environment.GetEnvironmentVariable("ASPNETCORE_ENVIRONMENT"), "Development", StringComparison.OrdinalIgnoreCase);
            
            if (isDevelopment)
            {
                var npmScriptProcess = new Process
                {
                    StartInfo = new ProcessStartInfo
                    {
                        FileName = "npm",
                        Arguments = $"run {_npmScript}",
                        RedirectStandardError = true,
                        RedirectStandardInput = true,
                        RedirectStandardOutput = true,
                        UseShellExecute = false,
                        WorkingDirectory = _sourcePath
                    }
                };

                npmScriptProcess.Start();
                _npmScriptStarted = true;
            }
        }

        // Call the next delegate/middleware in the pipeline
        await _next(context);
    }
}
public static class NpmMiddlewareExtensions
{
    public static IApplicationBuilder UseNpmScript(this IApplicationBuilder builder, string sourcePath, string npmScript)
    {
        return builder.UseMiddleware<NpmMiddleware>(sourcePath, npmScript);
    }
}

并在Program.cs（或startup.cs文件，如果有的话）文件中使用它。

public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
    // ... other middlewares ...

    app.UseNpmScript("ClientApp", "start");

    // ... remaining configuration ...
}