babel-plugin-transform-optional-chaining

The Optional Chaining Operator allows you to handle properties of deeply nested
objects without worrying about undefined intermediate objects.

Example

$3

``js
const obj = {
foo: {
bar: {
baz: 42,
},
},
};

const baz = obj?.foo?.bar?.baz; // 42

const safe = obj?.qux?.baz; // undefined

// Optional chaining and normal chaining can be intermixed
obj?.foo.bar?.baz; // Only access foo if obj exists, and baz if
// bar exists
`

$3

`js
const obj = {
foo: {
bar: {
baz() {
return 42;
},
},
},
};

const baz = obj?.foo?.bar?.baz(); // 42

const safe = obj?.qux?.baz(); // undefined
const safe2 = obj?.foo.bar.qux?.(); // undefined

const willThrow = obj?.foo.bar.qux(); // Error: not a function

// Top function can be called directly, too.
function test() {
return 42;
}
test?.(); // 42

exists?.(); // undefined
`

$3

`js
const obj = {
foo: {
bar: {
baz: class {
},
},
},
};

const baz = new obj?.foo?.bar?.baz(); // baz instance

const safe = new obj?.qux?.baz(); // undefined
const safe2 = new obj?.foo.bar.qux?.(); // undefined

const willThrow = new obj?.foo.bar.qux(); // Error: not a constructor

// Top classes can be called directly, too.
class Test {
}
new Test?.(); // test instance

new exists?.(); // undefined
`

Installation

`sh
npm install --save-dev babel-plugin-syntax-optional-chaining
`

Usage

$3

.babelrc

`json
{
"plugins": ["syntax-optional-chaining"]
}
`

$3

`sh
babel --plugins syntax-optional-chaining script.js
`

$3

`javascript
require("babel-core").transform("code", {
plugins: ["syntax-optional-chaining"]
});
``

References

* Proposal: Optional Chaining