js得到多维数组中相同键的值

function jstest(){var arr=[{'key1':'value1','key2':'value2','key3':'value3'},{'key1':'value4','key2':'value5','key3':'value6'},{'key1':'value7','key2':'value8','key3':'value9'}] ;var obj={};var narr=new Array();for(var i=0;i<arr.length;i++){for(var j in arr[i]){if(obj[j]!=undefined)obj[j]+=arr[i][j];elseobj[j]=arr[i][j];}}for(var i in obj){narr.push(eval("({'"+i+"':'"+obj[i]+"'})"));}//alert(narr[0].key1);alert(narr[1].key2);}