Often in TypeScript, you want to have all of the possible enum keys as an array when working with enums. Typical use cases are dropdown or other selection components based on enums. Using the…
Tuple 可以 convert 去 Union (下面会教), 但是反过来就不行. 参考:这个和这个(主要原因是 Union 是没有顺序概念的, Tuple 却是有的,有去没有 ok,没有去有则不行) type MyArrayType = [string, number,boolean];//用 JS 来描述大概是这样const myArrayType = ['string', 'number', 'boolean']; 有...
在示例中，convertToUpperCase 函数的主体逻辑与 JavaScript 中的逻辑完全一致（除了添加的参数类型注解）。在 TypeScript 中，第 3 行和第 5 行的 typeof、Array.isArray 条件判断，除了可以保证转译为 JavaScript 运行后类型是正确的，还可以保证第 4 行和第 6 行在静态类型检测层面是正确的。很明显，第 4 行...
For example, we declare an array of names, then we will use the reduce() to apply a function to each item of an array it will reduce the array to a single value. here the function will concatenate each item of an array with a separator string, creating a new string. In the convert...
var getEnumPropertyNames = function (obj) { if (typeof obj !== 'object') throw TypeError(); // 参数必须是对象 var props = []; // 将要返回的数组 for (var prop in obj) { // 遍历所有可枚举的属性 if (obj.hasOwnProperty(prop)) { //判断是否是自有属性 ...
The string-based enums operate the same as the numeric-based enums, but each variable has to be initialized in the string-based enum. If a variable needs to empty, it must be declared as an empty string. Example Code: enumstringEnum{a="Hello",b="Bye",c="",}console.log(stringEnum...
Because string enums naturally map to string values, converting an enum to a string is simple: enum Status { Processing = "PROCESSIING", Complete = "COMPLETE", Suspend = "SUSPEND" } // Convert enums to string const currentStatus: Status = Status.Processing; const statusString: string = ...
Infer function return types- Adds explicit return type annotations to functions. Add/remove braces from arrow function- Converts single line arrow function to multiline and back. Quick Fixes Quick Fixes are suggested edits that address simple coding errors. Example Quick Fixes include: ...
With the advent of the Map constructor accepting an iterable of entries, and its associated entries iterator (WeakMap also accepts iterable entries in its constructor), it becomes very compelling to want to quickly convert a plain object to a Map, via passing an array of entries into new Map...
In TypeScript 3.4, thereadonlymodifier in a mapped type will automatically convert array-like types to their correspondingreadonlycounterparts. Copy // How code acts now *with* TypeScript 3.4// { readonly a: string, readonly b: number }typeA=Readonly<{ a:string, b:number}>;// readonly...