It is an ES2015 destructuring assignment. More specifically, it's Object Destructuring

It might help to see it rewritten in a more verbose way.

const abc =;
const def = Object.def;

It's a syntatically terse way of extracting properties from objects, into variables.

// you can rewrite this
const name =;
const version = app.version;
const type = app.type;

// as this
const { name, version, type } = app;

Browser vendors are still implementing the ES2015 specification which is probably why it didn't work in your browser.

However, there's a project called Babel which allows you to convert future specifications of Javascript back into ES5. You can try out ES2015 code in their REPL.