在.Net中執行js

利用Noesis.Javascript開源組件可以做到在.net中執行js腳本，同時js腳本也能調用C#函數。這個組件的獲得方式：在NuGet中輸入搜索"Noesis"就能找到。

我們來做個搜索功能：用戶能夠在textbox中輸入js腳本來篩選list記錄，界面如下：

然后，click filter button后的UI：

看，篩選出來了，代碼如下（js能調C#寫的UserInfo類的各個屬性）

public class UserInfo
    {
        public string FirstName { get; set; }
        public string LastName { get; set; }
        public int Age { get; set; }
        public override string ToString()
        {
            return string.Format("{0}, {1}: {2}", FirstName, LastName, Age);
        }
    }

private void btnSearch_Click(object sender, EventArgs e)
        {
            List<UserInfo> users = FilterUsers(txtFilter.Text.Trim());
            lstUsers.DataSource = users;
        }

        private List<UserInfo> FilterUsers(string jsFilter)
        {
            List<UserInfo> results = new List<UserInfo>();
            if (jsFilter.Trim().Length == 0)
                return this.users;

            try
            {
                using (JavascriptContext context = new JavascriptContext())
                {
                    foreach (UserInfo user in this.users)
                    {
                        context.SetParameter("user", user);
                        context.SetParameter("isInclude", false);
                        string js = string.Format(@"
                                                if({0})
                                                    isInclude=true;
                                                else
                                                    isInclude=false;", jsFilter);
                        context.Run(js);
                        bool isInclude = (bool)context.GetParameter("isInclude");
                        if (isInclude) results.Add(user); } }
            }
            catch
            {
                txtFilter.Focus();
                txtFilter.SelectAll();
                return this.users;
            }

            return results;
        }

 

我們來看看效率：

private void btnTest_Click(object sender, EventArgs e)
        {
            using (JavascriptContext context = new JavascriptContext())
            {
                Stopwatch sw = new Stopwatch();
                sw.Start();
                int i=1000000;
                while(i-- > 0)
                {
                    context.SetParameter("ii", 1);
                    context.SetParameter("jj", 2);
                    context.SetParameter("sum", 0);
                    string js = string.Format(@"sum=ii+jj;");
                    context.Run(js);
                    int sum = (int)context.GetParameter("sum");
                }
                sw.Stop();

                long useJS_Total = sw.ElapsedMilliseconds;
                float useJS_Average = ((float)sw.ElapsedMilliseconds) / 1000000;

                sw.Reset();
                sw.Start();
                i = 1000000;
                while (i-- > 0)
                {
                    int ii = 1;
                    int jj = 2;
                    int sum = 0;
                    sum = ii + jj;
                }
                sw.Stop();

                long nouseJS_Total = sw.ElapsedMilliseconds;
                float nouseJS_Average = ((float)sw.ElapsedMilliseconds) / 1000000;

                string msg = "";
                msg += string.Format("useJS_Total: {0}\r\n", useJS_Total);
                msg += string.Format("useJS_Average: {0}\r\n\r\n\r\n", useJS_Average);
                msg += string.Format("nouseJS_Total: {0}\r\n", nouseJS_Total);
                msg += string.Format("nouseJS_Average: {0}\r\n\r\n\r\n", nouseJS_Average);

                MessageBox.Show(msg);
            }
        }

 

結果（上面的是通過js引擎計算的時間、下面的是純C#計算時間，悲劇啊）：

結論：

1. 這個Noesis.Javascript只適用於性能要求不高的場合
2. 高性能的要看Lua