How are json field referenced directly in javascript instead of as strings?

Question

Brand new to javascript. Used to strong typed Object oriented languages like Java and C#.

I am looking over some existing express javascript code that handles a request body.

const username = req.body.username

From what I understand username is a field passed in json. How is there a field on body that is called username already?

I was expected to see something like this...

const username = req.body['username']

Can anyone clarify what is going on here?

this: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Property_accessors - MDN is your reference for anything JavaScript. Google "MDN _anything here_" to get instant answers. — Randy Casburn, Dec 02 '21 at 18:15
@Scorb Out of interest, why did you expect the `body` property to be accessed with the dot notation but the `username` property to be accessed with the bracket notation? Is that something from the previous languages? — Matt, Dec 03 '21 at 00:05
Does this answer your question? [JavaScript property access: dot notation vs. brackets?](https://stackoverflow.com/questions/4968406/javascript-property-access-dot-notation-vs-brackets) — Matt, Dec 03 '21 at 00:10

score 1 · Answer 1 · edited Dec 03 '21 at 00:10

1

How is there a field on body that is called username already?

Because the middleware that processes the incoming HTTP request put it there.

I was expected to see something like this...

The dot or bracket notation is different syntax for accessing the same property.

edited Dec 03 '21 at 00:10

Matt

answered Dec 02 '21 at 18:15

Quentin

1 Answers1