20192020 Update
JavaScript now has equivalents for both the Elvis Operator and the Safe Navigation Operator.
Safe Property Access
The optional chaining operator (?.) is currently a stage 4 ECMAScript proposal. You can use it today with Babel.
// `undefined` if either `a` or `b` are `null`/`undefined`. `a.b.c` otherwise.
const myVariable = a?.b?.c;
The logical AND operator (&&) is the "old", more-verbose way to handle this scenario.
const myVariable = a && a.b && a.b.c;
Providing a Default
The nullish coalescing operator (??) is currently a stage 4 ECMAScript proposal. You can use it today with Babel. It allows you to set a default value if the left-hand side of the operator is a nullary value (null/undefined).
const myVariable = a?.b?.c ?? 'Some other value';
// Evaluates to 'Some other value'
const myVariable2 = null ?? 'Some other value';
// Evaluates to ''
const myVariable3 = '' ?? 'Some other value';
The logical OR operator (||) is an alternative solution with slightly different behavior. It allows you to set a default value if the left-hand side of the operator is falsy. Note that the result of myVariable3 below differs from myVariable3 above.
const myVariable = a?.b?.c || 'Some other value';
// Evaluates to 'Some other value'
const myVariable2 = null || 'Some other value';
// Evaluates to 'Some other value'
const myVariable3 = '' || 'Some other value';