Null-safe property access (and conditional assignment) in ES6/2015

Update (2022-01-13): Seems people are still finding this, here's the current story:

• Optional Chaining is in the specification now (ES2020) and supported by all modern browsers, more in the archived proposal: https://github.com/tc39/proposal-optional-chaining
• babel-preset-env: If you need to support older environments that don't have it, this is probably what you want https://babeljs.io/docs/en/babel-preset-env
• Babel v7 Plugin: https://babeljs.io/docs/en/babel-plugin-proposal-optional-chaining

Update (2017-08-01): If you want to use an official plugin, you can try the alpha build of Babel 7 with the new transform. Your mileage may vary

https://www.npmjs.com/package/babel-plugin-transform-optional-chaining

Original:

A feature that accomplishes that is currently in stage 1: Optional Chaining.

https://github.com/tc39/proposal-optional-chaining

If you want to use it today, there is a Babel plugin that accomplishes that.

https://github.com/davidyaha/ecmascript-optionals-proposal

It's not as nice as the ?. operator, but to achieve a similar result you could do:

user && user.address && user.address.postcode

Since null and undefined are both falsy values (see this reference), the property after the && operator is only accessed if the precedent it not null or undefined.

Alternatively, you could write a function like this:

function _try(func, fallbackValue) {
    try {
        var value = func();
        return (value === null || value === undefined) ? fallbackValue : value;
    } catch (e) {
        return fallbackValue;
    }
}

Usage:

_try(() => user.address.postcode) // return postcode or undefined 

Or, with a fallback value:

_try(() => user.address.postcode, "none") // return postcode or a custom string