Alex Jingjie Lu

Programming language:Whatever

2021-07-21 11:56:41

0

Q:

optional chain operator

CCS

Code: Whatever

2021-04-11 10:40:15

let myMap = new Map();
myMap.set("foo", {name: "baz", desc: "inga"});

let nameBar = myMap.get("bar")?.name;

1

雪儿徐

Code: Whatever

2021-04-11 10:38:49

/* 
* optional chaining (?.) allows me to write code that stops 
* running when we encounter a null or undefined value
*/

function tryGetFirstElement<T>(arr?: T[]) {
    return arr?.[0];
    // equivalent to
    //   return (arr === null || arr === undefined) ?
    //       undefined :
    //       arr[0];
}

1

technical_difficulty

Code: Whatever

2021-10-04 21:35:20

const array = [1,2,3,4,5];
let arrItem = array?.[4]; 

console.log(arrItem); /// 5

0

Jm san diego

Code: Whatever

2021-04-11 10:41:22

const adventurer = {
  name: 'Alice',
  cat: {
    name: 'Dinah'
  }
};

const dogName = adventurer.dog?.name;
console.log(dogName);
// expected output: undefined

0

Related

• matrix chain multiplication
• ternary operator for multiple conditions