CODEWITHSUNDEEP
javascriptjqueryajax
katie hudson
katie hudson

Reputation: 2893

Event firing when it shouldnt

I found some code which enables me to obtain URL query strings

var QueryURL = function () {
      var query_url = {};
      var query = window.location.search.substring(1);
      var vars = query.split("&");
      for (var i=0;i<vars.length;i++) {
        var pair = vars[i].split("=");
        if (typeof query_url[pair[0]] === "undefined") {
          query_url[pair[0]] = decodeURIComponent(pair[1]);
        } else if (typeof query_url[pair[0]] === "string") {
          var arr = [ query_url[pair[0]],decodeURIComponent(pair[1]) ];
          query_url[pair[0]] = arr;
        } else {
          query_url[pair[0]].push(decodeURIComponent(pair[1]));
        }
      }
      return query_url;
}();

The above code works perfectly. There is something I am not quite getting however. I am doing the following

$( ".search" ).click(function(e) {

    console.log(QueryURL.someID); //outputs undefined

    if(QueryURL.someID !==  "undefined") {
        $.ajax({
            url: "someurl",
            type: "POST",
            success: function (data) {
              console.log(data)
            },
            error: function(xhr, ajaxOptions, thrownError){
            }
        });
    }
});

So if I do not provide the URL with a query someID, then it should not execute the Ajax call. Now the console logging outputs undefined, as I expect it too. However, for some reason it is still firing the Ajax request even though I have a condition that should stop this from happening.

Why would it still make the ajax request if QueryURL.someID is undefined?

Thanks

Upvotes: 0

Views: 31

Answers (1)

barbsan
barbsan

Reputation: 3458

"undefined" is a string, you need to compare with variable undefined

if(QueryURL.someID !== undefined) { //ajax call }

From MDN:

The global undefined property represents the primitive value undefined. It is one of JavaScript's primitive types.

Upvotes: 1

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