There are already official proposals for those. See: https://github.com/tc39/proposals <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 <http://n.name/> !== null && u.name <http://u.name/> !== > undefined) ? u.name <http://u.name/> : u.name <http://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
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