optional chaining
let myMap = new Map();
myMap.set("foo", {name: "baz", desc: "inga"});
let nameBar = myMap.get("bar")?.name;optional chaining
let myMap = new Map();
myMap.set("foo", {name: "baz", desc: "inga"});
let nameBar = myMap.get("bar")?.name;optional chain operator
const adventurer = {
name: 'Alice',
cat: {
name: 'Dinah'
}
};
const dogName = adventurer.dog?.name;
console.log(dogName);
// expected output: undefinedoptional chaining
/*
* 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];
}optional chaining
const greeting = object?.deepProp?.deeperProp?.greetOptional chaining
let x = foo?.bar();
if (foo?.bar?.baz) { // ... }optional chaining
const array = [1,2,3,4,5];
let arrItem = array?.[4];
console.log(arrItem); /// 5Copyright © 2021 Codeinu
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