js Cannot set property 'color' of undefined

if(cToObj.pack == 1 ){

$("input[name='pack']").attr("checked","checked"); 
    $("#s_pack").style.color="#ff0000";

// $("#s_pack").css("color","red");

alert("该包裹需要加强包装，请注意！");
}

运行报错 Cannot set property 'color' of undefined是怎么回事？

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$("#s_pack")[0].style.color = "#ff0000" || $("#s_pack").css("color","#ff0000");
 

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jQuery对象没有style属性，样式通过css设置