如何优化 Typescript 中的 if 语句

Question

After declaring two variables param01 and param02 I go ahead and check if the incoming event.pathParameters is not undefined :

      let param01, param02;

      if (event.pathParameters!=undefined) {
        if (event.pathParameters.param01!=undefined) {
          param01 = event.pathParameters.param01;
        }
        if (event.pathParameters.param02!=undefined) {
          param02 = event.pathParameters.param02;
        }
      }    

While it works fine, it takes 10 lines of code. I wonder if there is a shorter and more elegant way of getting it done in Typescript

Answer 1

You can try something like this:

const param01 = event.pathParameters && event.pathParameters.param01 || null;
const param02 = event.pathParameters && event.pathParameters.param02 || null;

or using just one line:

const { param01, param02 } = event.pathParameters || {};

If your environment allows, you can also use Optional chaining .

const param01 = event.pathParameters?.param01; // value or undefined
const param02 = event.pathParameters?.param02; // value or undefined

Answer 2

You can use the ? operator

let param01 = event.pathParameters?.param01 || null;
let param02 = event.pathParameters?.param02 || null;