function myFunc(maybeString: string | undefined | null) { // Type 'string | null | undefined' is not assignable to type 'string'. // Type 'undefined' is not assignable to type 'string'. const onlyString: string = maybeString; // Error const ignoreUndefinedAndNull: string = maybeString!
export function parseSourceFile(fileName: string, sourceText: string, languageVersion: ScriptTarget, syntaxCursor: IncrementalParser.SyntaxCursor, setParentNodes?: boolean, scriptKind?: ScriptKind): SourceFile { scriptKind = ensureScriptKind(fileName, scriptKind); initializeState(sourceText, languageVers...
'@typescript-eslint/prefer-return-this-type': 'off', // 使用 String#startsWith 而不是其它方式 '@typescript-eslint/prefer-string-starts-ends-with': 'off', // async 函数的返回值必须是 Promise '@typescript-eslint/promise-function-async': 'off', // 强制get()类型应该可分配给其等效set(...
// Type 'string' is not assignable to type 'number'. } Notice that whether or notSourceis compatible withTargethas to do with whether theirpropertiesare assignable. In this case, that’s justprop. When you introduce generics into this, there are some harder questions to answer. For instance...
// strictNullChecks:true时下面一行会报错 let str: string = null 上述连个配置均为 strict: true配置导致的, 如果你想简单可以将其注释掉, 因为 strict 默认为 false, 上述两个配置默认也是 false strict: true //启用所有严格类型检查选项。 // 启用 --strict相当于启用 --noImplicitAny, --noImplicit...
// Type 'string' is not assignable to type 'number'. } Notice that whether or not Source is compatible with Target has to do with whether their properties are assignable. In this case, that’s just prop. When you introduce generics into this, there are some harder questions to answer. ...
Number 或 String 'no-new-wrappers': 2, // 禁止 new 一个类而不存储该实例 'no-new': 2, // 禁止把原生对象 Math、JSON、Reflect 当函数使用 'no-obj-calls': 2, // 禁止使用八进制转义符 'no-octal-escape': 2, // 禁止使用0开头的数字表示八进制 'no-octal': 2, // 禁止使用 __...
icon?:string; 图标,一般配合菜单使用。 auth?:boolean; 是否需要登录权限。 ignoreAuth?:boolean; 是否忽略权限。 roles?:RoleEnum[]; 可以访问的角色 keepAlive?:boolean; 是否开启页面缓存 hideMenu?:boolean; 有些路由我们并不想在菜单中显示,比如某些编辑页面。
Retrieving enums from string values Usually, we compare a string against the possible enum values to convert it back to an enum value. One way to accomplish this is by directly checking the enum values or using a type guard method: function isValidStatus(status: string): status is Status ...
interfaceCanCheck{checkThing:(x:string)=>boolean;} and implement it with an object: constobj={checkThing:(sn:string|number)=>{returntrue;}}objsatisfiesCanCheck;// OK A common confusion is to say that sincestring | numberis a bigger type thanstring, this program should be rejected, since...