Copy an Array with the Spread Operator

Nested Destructuring for Objects

Copy an Object with the Spread Operator

Merge Arrays using the Spread Operator

Flatten a Nested Array in JavaScript with Array.prototype.flat

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For...in Loop vs. For...of Loop

Array.prototype.flatMap from ES2019

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Safely Access a Property on a JavaScript Object with Optional Chaining

Safely Access a Property on a JavaScript Array with Optional Chaining

ES6 and Beyond

You can use optional chaining to access properties of an object. If the parent property exists, it acts as a typical dot accessor. If not, optional chaining prevents an error from being thrown and instead returns undefined.

Laurie Barth: [0:01] Define an object with an internal key-value pair {node: 1}. Object.node is equivalent to 1. If we use optional chaining ?., we still get 1.

[0:17] Define a new object that's null. If we attempt to access node on this object, we'll get an error. If we use optional chaining, we'll instead receive undefined.

Course

ES6 and Beyond

Safely Access a Property on a JavaScript Object with Optional Chaining

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