并且您想要一个简单的具有编译时和运行时安全性的string-to-Enum转换器，下面的方法效果很好：...
问如何在TypeScript中将字符串转换为枚举？EN在应用程序中，我们经常需要将日期字符串转换为日期对象。在...
Union type is nice and all, but I'm looking into making an enum for the main purpose of maintainability in the event that a string needs to be renamed. I might use the string literal "apple" in multiple places in the codebase, but using an enum gives me an easy way to rename thing...
functionfn(x:string) {console.log("Hello, "+ x.toLowerCase()); }typeStringOrNumberFunc=(ns:string|number) =>void;letfunc:StringOrNumberFunc= fn;// 不能将类型“(x: string) => void”分配给类型“StringOrNumberFunc”。// 参数“x”和“ns” 的类型不兼容。// 不能将类型“string | num...
enumDirection{Up="UP",Down="DOWN",Left="LEFT",Right="RIGHT",}letmove:Direction=Direction.Up;// "UP" 实用场景:定义有限的选项(如状态码、方向)。 8.类型守卫 (Type Guards) 通过条件判断收窄类型范围。 functionisString(value:any):valueisstring{returntypeofvalue==="string";}functionprocess(value...
let name: string = "Alice"; 符号型:symbol,表示唯一值。 let unique: symbol = Symbol("unique"); 空类型:undefined和null,表示未定义或空值。 let value: undefined = undefined; let nothing: null = null; 复杂数据类型 数组:使用数组类型来定义数组,例如number[]表示一个数字数组。
function safelyConvertToInt(value: any, defaultValue: number): number { if (typeof value === 'string') { return parseInt(value); } return value as number; } let stringValue = "42"; let intValue = safelyConvertToInt(stringValue, 1); ...
const x = "hello" as number;// Conversion of type 'string' to type 'number' may be a mistake because neither type sufficiently overlaps with the other. If this was intentional, convert the expression to 'unknown' first.有的时候，这条规则会显得非常保守，阻止了你原本有效的类型转换。如果发生...
In TypeScript, string literals allow you to specify the exact value a string must have in it’s lifespan. You can assume it a form as ‘string based enum’ which also is named group of string constants. TypeScript Enum In TypeScript, enums are set of named constants. Though it is op...
When we print this enum value in console, it prints enum variable numeric value like in the above example it prints 4 as 4 is the assigned value of Green. If we want to print enum name instead of number then we can assign it to any string variable and prints it. ...