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JavaScript Introducing ES2015 The Cooler Parts of ES2015 Destructuring

Posted by jlampstack
jlampstack
23,932 Points

First object parameter question....

At 3:40 Guil highlights the first object 

{url , method = 'post'} = {}

To me this looks like 2 objects, not 1. Also, why does the first {} have 2 properties, and the second {} has none?

Can someone please clarify. Thanks!

Ken S.
Ken S.
3,838 Points
Ken S.
Ken S.
3,838 Points

I had exactly the same question and didn't see this thread first. I guess many ppl have this question!

I understand what it does, but doesn't it seem pretty pointless in the example given?

2 Answers

Steven Parker
Steven Parker
231,275 Points
Steven Parker
Steven Parker
231,275 Points

The " = {}" part at the end defines a default for the parameter. It just means if nothing is provided as an argument, then an empty object will be used instead.

The first one actually defines the structure of the object that is expected, and you're right, it should have two properties. But it also has a default, so if the supplied argument has no "method" property (or if the empty default one is used), one will be created and set to "post".

jlampstack
jlampstack
23,932 Points
jlampstack
jlampstack
23,932 Points

I understand it now. Thanks. It just looked funny to me being the first time seeing something like this.