javascript optional chaining

You may write code in javascript like this:

if (foo && foo.bar && foo.bar.baz) { foo.bar.baz(); } 

We want to call baz() but first need check if foo , foo.bar, foo.bar.baz present. i think this is a little bit more prolixity.

Now you can write code like

foo?.bar?.baz() 

That all, just need use ?. operator, this called optional chainning. you need do something in babel config

// babel.config.js module.exports = { env: { ..... plugins: ['@babel/plugin-proposal-optional-chaining'] } } } 

More optional Channing example:

Dealing with optional callbacks or event handlers

function doSomething(onContent, onError) { try { // ... do something with the data } catch (err) { onError?.(err.message); // no exception if onError is undefined } } 

Optional chaining with expressions

let nestedProp = obj?.['prop' + 'Name']; 

Array item access with optional chaining

let arrayItem = arr?.[42]; 

You can found more api optional chainning

Hope it can help you :)