JavaScript文件錯誤，但不是控制檯？

Question

問題

Uncaught Error: The property or field has not been initialized. 
It has not been requested or the request has not been executed. 
It may need to be explicitly requested. 

在這裏的錯誤是代碼，只是想獲得一個列表的簡單計數。在oList.get_itemCount()發生

var CustomAction = function(){ 

    var clientContext = new SP.ClientContext.get_current(); 
    var web = clientContext.get_web(); 
    this.oList = web.get_lists().getByTitle("Classification"); 

    // .load() tells CSOM to load the properties of this object 
    // multiple .load()s can be stacked 
    clientContext.load(oList); 

    // now start the asynchronous call and perform all commands 
    clientContext.executeQueryAsync(Function.createDelegate(this, this.onSuccess), Function.createDelegate(this, this.onFailure)); 

    // method will exit here and onSuccess or OnFail will be called asynchronously 

}; 

function onSuccess(sender, args) { 
    alert('No of rows: ' + oList.get_itemCount()); 
}; 

function onFail(sender, args) { 
    alert('Request failed.\n' + args.get_message() + '\n' + args.get_stackTrace()); 
}; 

該錯誤。這會發生什麼原因？我嘗試使用$(document).ready和$(window).onload，但問題仍然存在。所以就像我說的那樣，當我複製/粘貼到瀏覽器中但是從文件中運行它時，它起作用。

Answer 1

試試這個

var CustomAction = function(){ 

    var clientContext = new SP.ClientContext.get_current(); 
    var web = clientContext.get_web(); 
    this.oList = web.get_lists().getByTitle("Classification"); 

    // .load() tells CSOM to load the properties of this object 
    // multiple .load()s can be stacked 
    clientContext.load(oList); 

    // now start the asynchronous call and perform all commands 

    clientContext.executeQueryAsync((function(sender, args){alert('No of rows: ' + oList.get_itemCount())}(this, this.onSuccess)), (function(sender, args){alert('Request failed.\n' + args.get_message() + '\n' + args.get_stackTrace())}(this, this.onFailure))); 
};