What the syntax in javascript? [closed]

Answer 1

The code can be broken down to this snippet, which contains weird stuff only:

const sth = function ( { test = true } = {} ){ }

So thats a function expression, but it has so called default parameters , that means if you dont pass a value, e.g.

sth();

This special part fills in the value for you:

= {}

So if you dont pass a value it rather takes an empty object. Now it goes on with object destructuring, take this example:

 const {key} = {key:"value"};
 console.log(key) // "value"

So object destructuring just moves the keys as variables into the context, the upper equals:

const key = {key:"value"}.key;

So now putting it all together:

{    
   audio_muted = false,
   trim_type = 0,
   source_type = 'camera',
   // ...
} = {}

This sets the variables audio_muted and so on based on the keys with the same name in the passed object and if they're not passed the values are set.