); } } function hasMethod(obj: any, methodName: string): obj is { [key: string]: (...args: any[]) => any } { return typeof obj[methodName] === "function"; } const myObj = new MyClass(); if (hasMethod(myObj, "myMethod")) { myObj.myMethod(); // 调用方法 } else...
UploadSummaryCommand.prototype.runCommandAsync =function(){var_this =this;varfilename =this.command.message;if(!filename) {returnQ(null); }vardeferred = Q.defer(); fs.exists(filename,function(exists){if(!exists) { deferred.resolve(null); }varprojectId = _this.executionContext.variables[ctxm...
To better model this behavior in instanceof, TypeScript now checks if such a [Symbol.hasInstance] method exists and is declared as a type predicate function. If it does, the tested value on the left side of the instanceof operator will be narrowed appropriately by that type predicate. Copy...
interfaceGenericType<T,U>{id:T;name:U;}functionshowType(args:GenericType<number,string>){console.log(args);}showType({id:1,name:'test'});// Output: {id: 1, name: "test"}functionshowTypeTwo(args:GenericType<string,string[]>){console.log(args);}showTypeTwo({id:'001',name:['This...
functionoptionallyModifyWebpackConfig(options: WebpackConfig | WebpackConfig[], command: Command){constpath = join(process.cwd(),'ws.config.js');constexists =existsSync(path);if(exists) {constmodifyWebpackConfig = __non_webpack_require__(path); ...
As developers, we often need to deal with values that aren’t fully known at runtime. In fact, we often don’t know if properties exist, whether we’re getting a response from a server or reading a configuration file. JavaScript’sinoperator can check whether a property exists on an obje...
Add the following to the gameTick function, beneath the curTick++ line of code:TypeScript 复制 if (curTick > START_TICK && curTick % 20 === 0) { // no terracotta exists, and we're waiting to spawn a new one. if (spawnCountdown > 0) { spawnCountdown--; if (spawnCountdown...
The core difference betweenanyandunknownis you are unable to interact with a variable of typeunknown; doing so generates acompilererror.anybypasses any compile-time checks, and the object is evaluated at runtime; if the method or property exists it will behave as expected. ...
If you are simply trying to implement watch-style functionality, we encourage you to explore the above watcher API.import * as fs from "fs"; import * as ts from "typescript"; function watch(rootFileNames: string[], options: ts.CompilerOptions) { const files: ts.MapLike<{ version: ...
interface Student { sid : number; name: string; }; function getName(std ?: Student): void { console.log("Name of the Student is ", std?.name); } If the std is undefined, it will display the following output: Name of the Student is undefined Syncfusion JavaScript controls allow you ...