function和=>有什么区别?在TypeScript中? [英] What's the difference between function and => in TypeScript?

问题描述

目前，我正在学习TypeScript.我对关键字函数和=>(胖箭头)之间的区别感到很困惑.请参见下面的代码:

Currently, I am learning TypeScript. I am quite confused about the difference between keyword function and => (fat arrow). Please see the code below:

interface Counter {
    (start: number);
    interval: number;
    reset() : void;
}

let a = <Counter>function(start: number) { };
let b = <Counter>(start: number) => { };

a.reset(); //OK
b.reset(); //error: Property 'reset' does not exist on type <Counter>(start: number) => void

胖箭头似乎与关键字功能不同.

It seems that fat arrow doesn't work the same as keyword function.

推荐答案

胖箭头函数的语法比函数表达式短，并且按词法绑定此值.箭头函数始终是匿名的，可以有效地将function (arguments) { return expression; }转换为(arguments) => expression.如果在箭头后面使用表达式，则返回值是隐式的，因此不需要返回值.

fat arrow functions have a shorter syntax compared to function expressions and lexically bind the this value. Arrow functions are always anonymous and effectively turn function (arguments) { return expression; } into (arguments) => expression. If using an expression after an arrow, the return is implicit, so no return is required.

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