The switch statement is used to check for multiple values and executes sets of statements for each of those values. A switch statement has one block of code corresponding to each value and can have any number of such blocks. When the match to a value is found, the corresponding block of ...
It executes all the cases and print the respective values. Open Compiler var grade: string = 'A'; console.log("Entering switch block"); switch(grade) { case "A": { console.log("Excellent"); } case "B": { console.log("Good"); } case "C": { console.log("Fair"); } case "...
二者之间的区别是TypeScript是静态类型,js是动态类型(详见强类型、弱类型、静态类型、动态类型的区别)。 弱类型语言(js)是据类型可以被忽略的语言。它与强类型定义语言相反, 一个变量可以赋不同数据类型的值。 强类型语言(ts)是强制数据类型定义的语言。也就是说,一旦一个变量被指定了某个数据类型,如果不经过强制...
第二种: <!DOCTYPE html> <html lang="en"> <head> <meta charset="utf-8"> <title>原生js实现多选功能</title> </head> <body> <div> <label>多选功能:</label> <select id="multipleSelect"> <option selected="selected" disabled="disabled" style='display: none' value=''></option> <opti...
functiongetValues<T,K extends keyofT>(obj:T,keys:K[]):T[K][]{returnkeys.map(key=>obj[key]);} 说明 泛型定义: T 是一个泛型类型参数,表示传入函数的第一个参数 obj 的类型。它可以是任何对象类型。 K extends keyof T 是另一个泛型类型参数,其中 K 必须是 T的键(即对象的属性名)的类型。这...
// "noFallthroughCasesInSwitch": true, /* Enable error reporting for fallthrough cases in switch statements. */ // "noUncheckedIndexedAccess": true, /* Include 'undefined' in index signature results */ // "noImplicitOverride": true, /* Ensure overriding members in derived classes are mark...
const msg = 'hello world' msg.toUperCase() 静态类型检查 在代码运⾏前进⾏检查,发现代码的错误或不合理之处,减⼩运⾏时出现异常的⼏率,此种检查叫静态类型检查,TypeScript 的核⼼就是静态类型检查,简⾔之就是把运⾏时的错误前置。 同样的功能,TypeScript 的代码量要⼤于 JavaScript,但由于...
function handleValue(val: All) { switch (val.type) { case 'foo': // 这里 val ...
*/ // "noFallthroughCasesInSwitch": true, /* Enable error reporting for fallthrough cases in switch statements. */ // "noUncheckedIndexedAccess": true, /* Add 'undefined' to a type when accessed using an index. */ // "noImplicitOverride": true, /* Ensure overriding members in ...
TypeScript now allows code completion to generate the various “case:” cases in its switch case statement when switching over restricted value sets like enums or literal types TypeScript 4.7 introduced a stricter module resolution. Because this sometimes didn’t fit the behavior of module bundlers...