interfaceAdmin{name:string;privileges:string[];}interfaceEmployee{name:string;startDate:Date;}type UnknownEmployee=Employee|Admin;functionprintEmployeeInformation(emp:UnknownEmployee){console.log("Name: "+emp.name);if("privileges"inemp){console.log("Privileges: "+emp.privileges);}if("startDate"inemp...
One consequence of using noUncheckedIndexedAccess is that indexing into an array is also more strictly checked, even in a bounds-checked loop. function screamLines(strs: string[]) { // This will have issues for (let i = 0; i < strs.length; i++) { console.log(strs[i].toUpperCase...
TypeScript While Loop - Learn how to use the while loop in TypeScript for effective programming. Explore syntax, examples, and best practices.
Parameter'x'implicitly has an'any'typeParameter'y'implicitly has an'any'type 该提示信息告诉我们:参数 x 和参数 y 隐式具有any类型。为了解决这个问题,就要给参数定义类型。 此时我们希望sum函数的入参可以同时支持string和number类型,所以我们可以先定义一个联合类型string | number,再给这个联合类型取个名字: ...
首先我们看左边 [Key in 'key1' | 'key2' | 'key3'] in 这个语法是 for loop 的意思. Key 是一个 Aliases 或 Variable 所以整句的意思是 for loop Union 然后把 String Literal 放入变量 Key. 用JS 表达大概就是 for(const key of ['key1', 'key2', 'key3']) {} ...
function error(msg: string): never { throw new Error('我报错了'); // 直接异常结束了 } function loop(): never { while (true) {} } function fn(x: number | string) { if (typeof x === 'number') { // 类型保护 console.log(x); } else if (typeof x === 'string') { consol...
The JSX Specification forbids the use of the}and>characters in text positions. TypeScript and Babel have both decided to enforce this rule to be more comformant. The new way to insert these characters is to use an HTML escape code (e.g.<span> 2 > 1 </span>) or insert an expression...
Value Explorer allows non-primitive runtime values to be viewed and explored in an easy-to-navigate real-time treeview. This feature is great for exploring larger objects and makes debugging easier and faster. Values can be copied directly to the clipboard. ...
h1 > Palindrome Example in TypeScript HTML App < /h1> < div id = "content" / > < /body> < /html> app.jsvar dowhile = (function() { function dowhile() {} dowhile.prototype.palimdrome = function() { var n; var s = 0; n = parseInt(prompt("Enter a Number fo...
type LoopStr<T extends string> = T extends `${infer P}${infer R}` // can do something with P ? `${P}${LoopStr<R>}` : ''; 该example没有任何实际意义,仅仅展示一下递归的方式 如果没有指定特定的子字符序列,P是每次都是字符串中的第一个字符,达到逐项遍历,你也可以给指定一个子序列,从...