EasyUI combobox动态增加选择项

<select id="workerList"></select>

if (!Array.prototype.forEach) {  
            Array.prototype.forEach = function(callback, thisArg) {  
                var T, k;  
                if (this == null) {  
                    throw new TypeError(" this is null or not defined");  
                }  
                var O = Object(this);  
                var len = O.length >>> 0; // Hack to convert O.length to a UInt32  
                if ({}.toString.call(callback) != "[object Function]") {  
                    throw new TypeError(callback + " is not a function");  
                }  
                if (thisArg) {  
                    T = thisArg;  
                }  
                k = 0;  
                while (k < len) {  
                    var kValue;  
                    if (k in O) {  
                        kValue = O[k];  
                        callback.call(T, kValue, k, O);  
                    }  
                    k++;  
                }  
            };  
        } 

 keyArray.forEach(function(x){
                                $("#workerList").append("<option value=\""+x+"\">"+x+"</option>");
                            })
$("#workerList").combobox(
                    {
                        editable:false,    
                        panelHeight:‘auto‘,
                        onSelect:function(param){ 
                              selectChange(param)
                              }
                     });