Question

I am new to JS, I made some investigation but couldn’t find a solution. Forgive me if it is a duplicate.

Context: I have thousands of objects, most of them the same properties. In the javascript, I get all the properties of objects and format them to show in html. Since some objects doesn’t have all the properties, i get undefined value. To solve this problem, I wrote this code:

var twitter = $.map(tweets, function(obj, index) {
                  return {                      
                     Format: ((typeof obj.VideographyFeatures.Format === "undefined") ? "N/A" : obj.VideographyFeatures.Format)
                  };
               });

But it doesn’t work. For the objects which don’t have “VideographyFeatures” property, I still get the following error.

“Uncaught TypeError: Cannot read property ‘Format’ of undefined”.

My aim is to get:

{
Format: "N/A"
};

Answer 1

If obj.VideographyFeatures is undefined, you cannot get its Format property to pass to the typeof expression.

You need to check typeof obj.VideographyFeatures.