Comparison of different examples of ajax and post processing json in jQuery_jquery

Recently, when I was making user comments on the portal, I hadn’t used jquery for a long time and I just happened to use it. I didn’t expect to cut corners and use the post method to process the json data of the ajax callback. I couldn’t get it, and there was json returned in the background. . Unexpectedly, such a small problem hung me up for several hours. Later, I handled it with the ajax method and it was OK. After a comparison, I found that the post method callback json must be eval, and the ajax method has been processed by default. Please be careful.

function haha() {
jQuery.post("addComment!comment.action",
function aa(data) {
data = eval(data);//POST方法必加，ajax方法自动处理了
alert(data[0].userId);
alert(data[0].userName);
},
"json"
);

jQuery.ajax({
type:"post",
url:"addComment!comment.action",
dataType:"json",
success: function aa(data) {
alert(data[0].userId);
alert(data[0].userName);
}
});
}

Backstage:

Configuration: