JavaScript使用警報，不工作沒有

Question

我寫了一個腳本，更新SharePoint列表中的一個字段的工作，但當我刪除警報（「測試」）;線停止工作。這裏是我的代碼：

<script type="text/javascript"> 

$(document).ready(function() { ExecuteOrDelayUntilScriptLoaded(loadConstants, "sp.js"); });   

function loadConstants() { 

    var userid= _spPageContextInfo.userId; 
    var requestUri = _spPageContextInfo.webAbsoluteUrl + "/_api/web/getuserbyid(" + userid + ")"; 
    var requestHeaders = { "accept" : "application/json;odata=verbose" }; 
    $.ajax({ 
     url : requestUri, 
     contentType : "application/json;odata=verbose", 
     headers : requestHeaders, 
     success : onSuccess, 
     error : onError 
    }); 

    function onSuccess(data, request){ 
     var loginName = data.d.Title; 

     var ctx = new SP.ClientContext("site name"); 
     var oList = ctx.get_web().get_lists().getByTitle('list name'); 
     this.oListItem = oList.getItemById(1);   

     ctx.load(this.oListItem); 
     ctx.executeQueryAsync(Function.createDelegate(this, function() {             
                this.oListItem.set_item('Read', loginName + ' ' + getTodayDate();); 
                }), function (sender, args) { alert('Error occured' + args.get_message());});  

     //HERE IS THE ALERT: 
     //alert("test"); 
     this.oListItem.update();    

     ctx.executeQueryAsync(
      Function.createDelegate(this, this.onQuerySucceeded), 
      Function.createDelegate(this, this.onQueryFailed) 
     ); 
    } 
    function onError(error) { 
     alert("error"); 
    } 
    function getTodayDate() { 
     //code that gets today's date 
     return today; 
    } 
} 

</script> 

在此先感謝您對此問題的任何幫助！

Answer 1

我不知道這個API，但它看起來像是傳遞了兩個回調到executeQueryAsync()。

第一個實際上首先傳遞給Function.createDelegate()。我認爲這會返回一個新的功能。無論如何，你傳遞給它的匿名函數似乎被用於響應查詢。因此，任何依賴於返回數據的代碼都應該放置在那裏 $（document）.ready（function（）{ExecuteOrDelayUntilScriptLoaded（loadConstants，「sp.js」）;}）;

function loadConstants() { 

    var userid= _spPageContextInfo.userId; 
    var requestUri = _spPageContextInfo.webAbsoluteUrl + "/_api/web/getuserbyid(" + userid + ")"; 
    var requestHeaders = { "accept" : "application/json;odata=verbose" }; 
    $.ajax({ 
     url : requestUri, 
     contentType : "application/json;odata=verbose", 
     headers : requestHeaders, 
     success : onSuccess, 
     error : onError 
    }); 

    function onSuccess(data, request){ 
     var loginName = data.d.Title; 

     var ctx = new SP.ClientContext("site name"); 
     var oList = ctx.get_web().get_lists().getByTitle('list name'); 
     this.oListItem = oList.getItemById(1);   

     ctx.load(this.oListItem); 
     ctx.executeQueryAsync(Function.createDelegate(this, function() {             
            this.oListItem.set_item('Read', loginName + ' ' + getTodayDate(); 

// run after the executeQueryAsync response arrives---vvvvvv 
            this.oListItem.update();    

            ctx.executeQueryAsync(
            Function.createDelegate(this, this.onQuerySucceeded), 
            Function.createDelegate(this, this.onQueryFailed) 
           ); 
           }), 
           function (sender, args) { 
            alert('Error occured' + args.get_message()); 
           });  
    } 
    function onError(error) { 
     alert("error"); 
    } 
    function getTodayDate() { 
     //code that gets today's date 
     return today; 
    } 
} 

所以，現在你.update()代碼不會被調用，直到返回響應查詢回調火災。