当我尝试检索对象时，sessionStorage不起作用

Question

I am using an AJAX call to a web method to validate a user, and when the web call returns, I am trying to use this code to populate sessionStorage with an object so I can then access the user's information from other pages:

 success: function (r) {
                    var info = JSON.parse(r.d);
                    if (info.Reply == 'OK')
                    {
                        $('#signinForm').html("<p>You're logged in!</p>");
                        var MemberObject = { 'MemberName': $('#MemberName').val() };
                        sessionStorage.setItem('MemberObject', JSON.stringify(MemberObject));
                    }
                },
                error: function (r) {
                    alert(r.responseText);
                },
                failure: function (r) {
                    alert(r.responseText);
                }

To test this, I added this block of code at the top of the page to replace the login dialogue with a welcome message for a logged-in user by retrieving the object I added to sessionStorage , but it doesn't work:

$(document).ready(function () {
        function isObject(val) {
            if (val === null) { return false; }
            return ((typeof val === 'function') || (typeof val === 'object'));
        }

        var mObj = sessionStorage.getItem('MemberObject');

        if (isObject(mObj))
        {
            var data = JSON.parse(mObj);
            $('signinForm').html("<p>Welcome, " + data.MemberName + "!</p>");
        }

Why doesn't sessionStorage working?

Answer 1

As @nnnnnn said in comment, the if (isObject(mObj)) condition will always return false. mObj is a string at that point in time. To resolve the problem, use JSON.parse() before the condition instead of after it, or use a different condition.