user2228656
user2228656
Programming language:Javascript
2021-05-17 11:21:36
0
Q:

conditional chaining chrome

Amitabha Roy
Amitabha Roy
Code: Javascript
2021-02-02 04:22:33 
const nameLength = db?.user?.name?.length; // property
const adminOption = db?.user?.validateAdminAndGetPrefs?.().option; // functions
const optionLength = db?.user?.preferences?.[optionName].length; // dynamic property
const userName = usersArray?.[userIndex].name; // on arrays
3
CCS
CCS
Code: Javascript
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
雪儿徐
Code: Javascript
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

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