function enumerable(value: boolean) { return function (target: any, propertyKey: string, descriptor:PropertyDescriptor) { descriptor.enumerable = value; }; }这里的 @enumerable(false) 装饰器是一个 装饰器工厂。当 @enumerable(false) 装饰器被调用时,它修改了属性描述符的 enumerable 属性。
Thanks to another pull request fromAlex Tarasyuk, you can now mark destructured variables as unused by prefixing them with an underscore (the_character). let[_first,second] =getValues(); Previously, if_firstwas never used later on, TypeScript would issue an error undernoUnusedLocals. Now,...
--noPropertyAccessFromIndexSignature abstract Construct Signatures The --explainFiles Flag Improved Uncalled Function Checks in Logical Expressions Destructured Variables Can Be Explicitly Marked as Unused Relaxed Rules Between Optional Properties and String Index Signatures Declare Missing Helper Function Breakin...
Each property in an object type can specify a couple of things: the type, whether the property is optional, and whether the property can be written to. Optional Properties Much of the time, we’ll find ourselves dealing with objects that might have a property set. In those cases, we can...
Optional Types If a component has an optional prop, add a question mark and assign during destructure (or use defaultProps). class MyComponent extends React.Component<{ message?: string; // like this }> { render() { const { message = "default" } = this.props; return <div>{message}<...
Since TypeScript 4.4, our condition on theplanproperty does not have to be directly accessed on theuservariable; TypeScript can also narrowuser's type from destructured properties, as follows: And, since the brand new TypeScript 4.5 release, theDiscriminated Unioncommon property can be defined ...
Tuples can be destructured into individual variables. This example extracts tuple elements into separate variables. destructure_tuple.ts let point: [number, number] = [10, 20]; let [x, y] = point; console.log(`X: ${x}, Y: ${y}`); // Output: X: 10, Y: 20 ...
Strict optional property checks with--strictOptionalProperties Useunknownfortry/catchvariables with--useUnknownInCatchVariables Updated--helpdescriptions Inlay Hints High-Confidence Suggestions in Unchecked JavaScript Quick Fix to Declare Missing Properties on Objects ...
eslint-plugin: more optional chain support in rules (#1363) (3dd1b02) eslint-plugin-tslint: add fixer for config rule (#1342) (c52c5c9) typescript-estree: computed members discriminated unions (#1349) (013df9a) typescript-estree: tighten prop name and destructure types (#1346) (f335...
In this case, the object being destructured is{ firstName: "Eve" }, which does have afirstNameproperty, so the value "Eve" is assigned to the constantfirstName. Theconsole.log(firstName)statement at the end will print "Eve" to the console....