I've also written an article onhow to check if an array contains a value in TS. I wrotea bookin which I share everything I know about how to become a better, more efficient programmer. You can use the search fi
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...
function padLeft(value: string, padding: string | number) { if (typeof padding === "number") { return Array(padding + 1).join(" ") + value; } if (typeof padding === "string") { return padding + value; } throw new Error(`Expected string or number, got '${padding}'.`); ...
interfaceArray<T>{[index:number]:T;// ...}letarr=newArray<string>();// 有效arr[0]="hello!";// 错误,这里需要一个「string」值arr[1]=123; 索引签名特别适用于在外部表达大量代码的情况;但到目前为止,索引签名仅适用于 string 及 number 键(而且 string 索引中还故意设置一项特性,即可以接受 numb...
let someArray = [1, "string",false];for(let entry of someArray) { console.log(entry);//1, "string", false} 二、for..in 方法 这个方法要注意和for..of的区别,for..in遍历的值是数组的索引 let list = [4, 5, 6];//for infor(let iinlist) { ...
maybeString != "string") || !sanitizeBar(checker.bar) ) { return false; } return true; } function sanitizeBar(checker: any) { if (!sanitizenumberArray(checker.numbers)) { return false; } return true; } function sanitizenumberArray(checker: any) { if (!Array.isArray(checker)) { ...
isArray(x): // 'x' is 'unknown' here. console.log(x.length); default: // 'x' is 'unknown' here. } } 此前这种写法内,各个 case 语句的 x 不会正常进行类型收窄,如 typeof x === "string" 成立时 x 应被收窄到 string 类型这样,5.3 版本已对此问题进行了修正。 布尔值比较 此前...
class SafeBox { #value: string | undefined; // Only accepts strings! set value(newValue: string) { } // Must check for 'undefined'! get value(): string | undefined { return this.#value; } } In fact, this is similar to how optional properties are checked under --exactOptionalPrope...
{suit: string; card: number; }[]): number; function pickCard(x: number): {suit: string; card: number; }; function pickCard(x): any { // Check to see if we're working with an object/array // if so, they gave us the deck and we'll pick the card if (typeof x == "...
Uint8Array→stringuint8ArrayToString() functionmergeUint8Array(a:Uint8Array,b:Uint8Array):Uint8Array;functionmergeAllUint8Arrays(arrays:ReadonlyArray<Uint8Array>):Uint8Array; import*asbinconvfrom'binconv';constblob=newBlob(["this is a blob"]);constreadableStream=binconv.blobToReadableStream(blo...