全面分析PostBack之Client Script

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function  WebForm_PostBackOptions(eventTarget, eventArgument, validation, validationGroup, actionUrl, trackFocus, clientSubmit)  {
    this.eventTarget = eventTarget;
    this.eventArgument = eventArgument;
    this.validation = validation;
    this.validationGroup = validationGroup;
    this.actionUrl = actionUrl;
    this.trackFocus = trackFocus;
    this.clientSubmit = clientSubmit;
}
 
function  WebForm_DoPostBackWithOptions(options)  {
    var validationResult = true;
    if (options.validation) {
        if (typeof(Page_ClientValidate) == 'function') {
            validationResult = Page_ClientValidate(options.validationGroup);
        }
    }

    if (validationResult) {
        if ((typeof(options.actionUrl) != "undefined") && (options.actionUrl != null) && (options.actionUrl.length > 0)) {
            theForm.action = options.actionUrl;
        }
        if (options.trackFocus) {
            var lastFocus = theForm.elements["__LASTFOCUS"];
            if ((typeof(lastFocus) != "undefined") && (lastFocus != null)) {
                if (typeof(document.activeElement) == "undefined") {
                    lastFocus.value = options.eventTarget;
                }
                else {
                    var active = document.activeElement;
                    if ((typeof(active) != "undefined") && (active != null)) {
                        if ((typeof(active.id) != "undefined") && (active.id != null) && (active.id.length > 0)) {
                            lastFocus.value = active.id;
                        }
                        else if (typeof(active.name) != "undefined") {
                            lastFocus.value = active.name;
                        }
                    }
                }
            }
        }
    }

    if (options.clientSubmit) {
        __doPostBack(options.eventTarget, options.eventArgument);
    }
}

按上面的分析我们已经知道什么情况下使用__doPostBack，什么情况下使用WebForm_DoPostBackWithOptions（options ）。

  分析一下Reflector出来的Button源码：
 
    有了这段代码，我们就可以很清晰的得到服务端如何决定采取什么方式来绘制客户端的PostBack Script了

DoPostBackWithOptions
1private string gDoPostBackWithOptions = "WebForm_DoPostBackWithOptions(new WebForm_PostBackOptions(/"{0}/", /"{1}/", {2}, /"{3}/", /"{4}/", {5}, {6}))";

   

IButtonControl button  =  (IButtonControl)control;

                     if  ((button.CausesValidation  &&  ( this .Page.GetValidators(button.ValidationGroup).Count  >  0 ))  ||  ! string .IsNullOrEmpty(button.PostBackUrl))
                     {
                        strOnClickScript = string.Format(gDoPostBackWithOptions, control.ClientID, button.CommandArgument, button.CausesValidation.ToString().ToLower(), button.ValidationGroup, button.PostBackUrl, "false", "true");
                    }
                     else
                     {
                        strOnClickScript = Page.ClientScript.GetPostBackEventReference(control, button.CommandArgument);
                    }

     至此KMessageBox服务端的封装工作全部结束。做到，不影响原来的编码方式，只需要简单的执行一下KMessageBox的RegisterConfrim函数为control注册一下客户端事件就搞定一切。  

OnPreRender
 1 if ((this.Page != null) && base.IsEnabled)
 2      {
 3            if ((this.CausesValidation && (this.Page.GetValidators(this.ValidationGroup).Count > 0)) || !string.IsNullOrEmpty(this.PostBackUrl))
 4            {
 5                  this.Page.RegisterWebFormsScript();
 6            }
 7            else if (!this.UseSubmitBehavior)
 8            {
 9                  this.Page.RegisterPostBackScript();
10            }
11      }
12

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