Ext.Ajax.request params动态获取后传入失败

[code="js"]
params = ''
for(var i=0;i<IfieldName.length;i++){
paramsValue = Ext.getDom(IfieldName[i]).value
if(paramsValue==undefined){paramsValue=''}
params = params+IfieldName[i]+':\''+paramsValue+'\','
}
params = params+'formID:\''+formID+'\''
params = '[{'+params+'}]'
params = eval(params)
Ext.Ajax.request({
url:"/DataOperate/exeFormInsert.asp",
params:params,
success:function(response){
eval(response.responseText)
loadList(page)
win.destroy();
}
})
[/code]

把params = '[{'+params+'}]'换成params = '({'+params+'})'试试？？