Excellent! Thanks so much for the pointers. These will be great syntactic improvements.
Cheers, Arash On Wed, Dec 20, 2017 at 12:12 AM, Claude Pache <[email protected]> wrote: > There are already official proposals for those. See: > > https://github.com/tc39/proposals > > and search for “Nullish coalescing Operator” for the first of your > suggestions and “Optional Chaining” for the second one. > > —Claude > > > > Le 20 déc. 2017 à 09:03, Arash Motamedi <[email protected]> a > écrit : > > I’d like to propose two new operators that I’ve appreciated using in C#, > with appropriate modifications for Ecmascript. > > ?? Null-Coalescing Operator > > The ?? operator is called the null-coalescing operator. It returns the >> left-hand operand if the operand is not null or undefined; otherwise it >> returns the right hand operand. (modified excerpt from C# definition, >> here >> <https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/operators/null-conditional-operator> >> .) > > > Examples: > > let u = undefined; > let nu = u ?? 0; > // nu = (u !== undefined && u !== null) ? u : 0 > > let n = null; > let nn = n ?? "Default"; > // nn = (n !== undefined && n !== null) ? n : "Default"; > > let p = someObj.someProp ?? "Hello"; > // p = (someObj.someProp !== undefined && someObj.someProp !== null) ? > someObj.someProp : "Hello"; > > The ?? operator allows for a very terse syntactic representation of a > rather common statement, and its value becomes very clear when evaluating > and accessing properties on objects, as illustrated in the 3rd example > above. For credit, comparison, and further details, please review the C# > null coalescing operator information here > <https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/operators/null-conditional-operator> > . > > > ?. Null Conditional Member Access and ?[ Null Conditional Index Access > > Used to test for null or undefined before performing a member access (?.) >> or index (?[) operation. (modified excerpt from C# definition here >> <https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/operators/null-conditional-operators> >> .) > > > Examples: > > let n = null; > let nn = n?.name; > // nn = (n.name !== null && u.name !== undefined) ? u.name : u.name; > > let p = {name: "John"}; > let l = p.lastName?.length; > // l = (u.lastName !== null && u.lastName !== undefined) ? > u.lastName.length : u.lastName; > > The ?. and ?[ operators allow for graceful access (as opposed to > null/undefined reference errors) to object members, and are particularly > useful when used in a chained manner. For credit, comparison, and further > details, please review the C# null conditional member access operator > information here > <https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/operators/null-conditional-operators> > . > > > Combining the above operators can enable very concise syntax for checking > against null/undefined and providing default values in a graceful manner. > > let lastNameLength = person.lastName?.length ?? 0; > let cityToUppercase = person.address?.city?.toUpperCase() ?? "N/A"; > > > Looking forward to working with the community and hopefully bringing these > two operators to the language. > > Best, > Arash > > _______________________________________________ > es-discuss mailing list > [email protected] > https://mail.mozilla.org/listinfo/es-discuss > > >
_______________________________________________ es-discuss mailing list [email protected] https://mail.mozilla.org/listinfo/es-discuss
