函数是应用程序的基本组成部分,在 TypeScript 中声明函数和 JavaScript 类似: function name(parameter: type, parameter:type,...): returnType { // do something }和 JavaScript 不同的是它允许你为参数和返…
function buildName(firstName: string, lastName?: string) { if (lastName) return firstName + " " + lastName; else return firstName; } In TypeScript, we can also set a value that a parameter will be assigned if the user does not provide one, or if the user passes undefined in its...
同样，在TypeScript 中也支持这样的参数类型定义，如下代码所示：function sum(...nums: number[]) {return nums.reduce((a, b) => a + b, 0);}sum(1, 2); // => 3sum(1, 2, 3); // => 6sum(1, '2'); // ts(2345) Argument of type 'string' is not assignable to parameter of ...
如果 strictFunctionTypes 设置为 true,则 Typescript 的参数进行逆变比较。 <pre class="prettyprint hljs typescript" style="padding: 0.5em; font-family: Menlo, Monaco, Consolas, "Courier New", monospace; color: rgb(68, 68, 68); border-radius: 4px; display: block; margin: 0px 0px 1.5em;...
import * as ts from 'typescript'; function getFunctionParameterTypes(sourceCode: string, functionName: string): ts.Type[] { const sourceFile = ts.createSourceFile('temp.ts', sourceCode, ts.ScriptTarget.Latest); const parameterTypes: ts.Type[] = []; function visit(node: ts.Node)...
function multiply(a: number, b: number) { return a * b; } Try it Yourself » If no parameter type is defined, TypeScript will default to using any, unless additional type information is available as shown in the Default Parameters and Type Alias sections below.Optional...
This apply to callback function, not normal function However, it cannot use a parameter that doesn't exist in its definition, as this would result in an error. This is why we needed to delete the first two members of theCallbackTypeunion. ...
expression, we can use the “infer” keyword to either get the type of the elements of an array, or even to get the return type of a function. We can use this to build a “FnReturnType” type, that will give us the return type of the function passed in as the generic parameter....
function foo(this: { name: string }, info: {name: string}) { console.log(this, info) } //1.ThisParameterType: 获取FooType类型中this的类型 type FnType=ThisParameterType<typeof foo> 1. 2. 3. 4. 5. 2、OmitThisParameter 用于移除一个函数类型Type的this参数类型,并且返回当前的函数类型 ...
function greet(name: string = "World") { console.log("Hello, " + name + "!"); }在上述代码中,`name`参数是可选的,因为它有一个默认值。🔍 如何检查可选参数是否已初始化? You can check if an optional parameter is initialized by accessing it within the function body.例如:typescript ...