Bummer! You must be logged in to access this page.

Welcome to the Treehouse Community

Want to collaborate on code errors? Have bugs you need feedback on? Looking for an extra set of eyes on your latest project? Get support with fellow developers, designers, and programmers of all backgrounds and skill levels here with the Treehouse Community! While you're at it, check out some resources Treehouse students have shared here.

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and join thousands of Treehouse students and alumni in the community today.

Start your free trial

JavaScript

Posted by brandonlind2
brandonlind2
7,823 Points

Can someone explain this different javascript syntax?

const neuron = ({ synapses = [], threshold = 1 } = {} /*im confused by these, it passes 
an object literal equal to an empty object? what?*/) => ({
  synapses,
  threshold
}/*im confused these (), after the arrow*/ );

//code without comments
const neuron = ({ synapses = [], threshold = 1 } = {}) => ({
  synapses,
  threshold
});

[mod edit - formatting]

1 Answer

Seth Kroger
Seth Kroger
56,416 Points

It's a combination of defaut paramenters and destructuring assignment, specifically this. The function will take an object as an argument but if synapses or threshold are missing it will supply the given defaults.

neuron();
  // returns { synapses: [], threshold: 1 }
neuron({synapses: [1,2]});
  // returns { synapses: [1,2], threshold: 1 }