Suggestion: "safe navigation operator", i.e. x?.y · Issue #16 · microsoft/TypeScript (original) (raw)

Description

Current Status

• The TC39 proposal is now at stage 3 (🎉🎉🎉🎉🎉)
• Implementation is in progress
• You can expect this feature in TypeScript 3.7
• We'll update here when it's available in a nightly build
• Holding off on Optional Call until its semantics are clarified at committee

Open questions

• What special-casing, if any, should document.all get?

C# and other languages have syntax sugar for accessing property chains where null (or in our case, undefined) might be encountered at any point in the object hierarchy.

var x = { y: { z: null, q: undefined } }; console.log(x?.y?.z?.foo); // Should print 'null' console.log(x?.baz); // Still an error console.log(x.y.q?.bar); // Should print 'undefined'

Need proposal on what exactly we should codegen, keeping in mind side effects of accessors.

Edit by @DanielRosenwasser February 27, 2018: This proposal is also called the "null propagation" operator.