if / else语句改为切换

Question

I have this ajax request :

    SJA.ajax(dataToSend, //this is internal method, which sends requests to the urls  
function (respond) {

      var categorySelect = that.$modal.find('.cat-post')[0].selectize; //using selectize.js plugin for selects. 

          if (respond) {
          callback && callback(respond);
          for (var i in respond) {
            //console.log(respond[i].id);
            //console.log(respond[i].name);
            categorySelect.addOption({value: respond[i].id, text: respond[i].name}); //adding new options to a select field.
          }
        }
    });
  var category: that.$modal.find('.cat-post').val() //this is option value in select field !== 'null' ? $('.cat-post').val() : null, //this variable is responsible for keeping selected data. 

And then I compare selected data (because I need to get some string value to use it in table):

var categoryName = 'all';
        switch (category) {
          case '0' // compare with respond id: 
            categoryName = "all" // compare with respond name ;
            break;
          case '1':
            categoryName = "Health";
            break;
          case '2':
            categoryName = "Cars";
            break;
        }

And after that I am adding new td in my table.

  $tbody.append(['<tr data-id="' + row.id + '">',
'<td class="restricted-view-hide view-mode2-hidden view-mode21-hidden">'  + categoryName + '</td>', '</tr>'].join(''));

But I don't want every time type new values in switch, I want to use something to receive dynamically new values. I have tried something like this:

categoryName = respond[i].id != null ? respond[i].name : "any";

bui it doesn't work. Any ideas?

Answer 1

Right. Assumptions:

1) you are aware that the conditional statement you have posted uses respond.id and respond.name, where your switch statement uses $(".cat-post").val(), and that these two methods are likely to return completely different values.

2) The conditional statement you have posted uses the variables you want it to use, and it's just not giving the expected answer - that is, in the situation where respond.id isn't valid it's not giving you "any".

If this is the case, then the solution is simple enough. An element with no id returns "" for .id, not null, so check whether respond.id != "", not != null.

categoryName = respond[i].id != "" ? respond[i].name : "any";

That said...

categoryName = respond[i].id != null ? respond[i].name : "any";

This just doesn't look right. It basically says "If my respond element has an id, then use its name value as categoryName". Is this what you want? Can you be sure that respond[i].name will always be valid if respond[i].id is? Why not just check whether respond[i].name is != ""? Is there some doubt over the validity of the name attribute if the id attribute isn't set? Using

categoryName = respond[i].name != "" ? respond[i].name : "any";

would appear on face value to make far more sense.

It's also worth noting that assumption 1) is a pretty big assumption. If your code is currently working the way you want it to, but you want to make it more flexible, unless there's some serious duplication of data going on (where $(.cat-post)[0].val() is set to some value determined by respond[i].name (or vice-versa)), implementing what you have above is going to break your code.

Note that this only really applies if your code is fundamentally working, but giving you the wrong values. if it's broken, not giving you any response at all, then you need to be more specific about what you mean by "it doesn't work".

Answer 2

Dunno if it could change anything but try :

categoryName = (respond[i].id != null) ? respond[i].name : "any";

instead maybe ^^