ES2018 | 12 New JavaScript Features

Publié le: 14 février 2018
sur la chaîne: CodeBig
2,889
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ES2018 - 12 New JavaScript Features

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 Info
----------------------------------------------------------------------------------------
Title: ES2018 - 12 New JavaScript Features
Level: Intermediate to Advanced
Language: Javascript
Length: 17 minutes
Prerequisites: Basics of JavaScript


// Rest elements for array destructuring assignment:
const primes = [2, 3, 5, 7, 11];
const [first, second, ...rest] = primes;
console.log(first); // 2
console.log(second); // 3
console.log(rest); // [5, 7, 11]

// Spread elements for array literals:
const primesCopy = [first, second, ...rest];
console.log(primesCopy); // [2, 3, 5, 7, 11]

Second code
const dude = {
name: 'Edmond',
age: 30,
role: 'Front End Developer',
}
const {name, ...details} = dude;
console.log(name);
console.log(details);

const details = {
age: 30,
role: 'Front End Developer',
}

const dude = {
name: 'Edmond',
...details
}
console.log(dude);

Third Code
// Shallow-clone an object:
const data = { x: 42, y: 27, label: 'Treasure' };
// The old way:
const clone1 = Object.assign({}, data);
// The new way:
const clone2 = { ...data };


Fourth Code
async function example(){

const arrayOfFetchPromises = [

fetch('https://api.github.com/users/teamCode...,

fetch('https://api.github.com/users/manojsm'),

fetch('https://api.github.com/users/charles')

];

// Regular iterator:
for (const item of arrayOfFetchPromises) {
console.log(item); // Logs a promise
}

//Async Iterator
for await (const item of arrayOfFetchPromises) {
console.log(item);
}

Fifth code
// Note the * after "function"
async function* asyncRandomNumbers() {
// This is a web service that returns a random number
const url = 'https://www.random.org/decimal-fracti...
while (true) {
const response = await fetch(url);
const text = await response.text();
yield Number(text);
}
}

Sixth Code
async function example() {
for await (const number of asyncRandomNumbers()) {
console.log(number);
if (number 0.95) break;
}
}

Seventh Code
fetch('https://api.github.com/users/teamCode...)
.then(response = response.json())
.then(data = console.log(data.name))
.catch(err = console.log(err))
.finally(() = console.log('All fetched'))

Eight code:
function tag (strs) {
" strs[0] === undefined "
" strs.raw[0] === "\\unicode and \\u{55}"; "
}
" tag '\unicode and \u{55}' "

Ninth code
/foo.bar/.test('foo\nbar');
// false
/foo.bar/s.test('foo\nbar');
// true

Tenth code
const re = /(?year\d{4})-(?month\d{2})-(?day\d{2})/u;
const result = re.exec('2019-01-29');
// result.groups.year === '2019';
// result.groups.month === '01';
// result.groups.day === '29';
// result[0] === '2019-01-29';
// result[1] === '2019';
// result[2] === '01';
// result[3] === '29';

Eleventh Code
'$10.53'.match(/(?=\$)\d+(\.\d*)?/)

Tewlth Code
const regexGreekSymbol = /\p{Script=Greek}/u;
regexGreekSymbol.test('π');


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