Add a extra property to each item of an array

Question

I have an array of items called documents. Each item has the same bunch of properties. I wanted to add an additional property to each item called serviceShortCode. I wrote the following code to achieve this

documents = _.map(documents, function (doc) {
                return _.extend({                    
                    serviceShortCode: View.getServiceName(doc.publishedIn)      
                });
            });

Once this code finishes executing I get an array of objects with only the serviceShortCode, all other properties have vanished.

Why so?

major-mann · Accepted Answer · 2014-07-09 10:50:29Z

1

You seem to be missing the document from the extend call.

Change

return _.extend({                    
    serviceShortCode: View.getServiceName(doc.publishedIn)
});

To

return _.extend(doc, {                    
    serviceShortCode: View.getServiceName(doc.publishedIn)
});

Or, alternatively

return _.extend({}, doc, {                    
    serviceShortCode: View.getServiceName(doc.publishedIn)
});

to ensure the original objects remain unmodified.

answered Jul 9, 2014 at 10:50

major-mann

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