shisama

const sourceCode = "{data: 'Hello, \u2028World'}";

eval(sourceCode) // 'Hello, World'

shisama

try {
  someFunc() // thorws Error
} catch {
  console.log('Error occurs')
}

shisama

const sourceCode = "{data: 'Hello, \u2028World'}";

eval(sourceCode) // SyntaxError: Invalid or unexpected token

shisama

export default () => {
  console.log("default export")
}
export function printArg(arg) {
  console.log(arg)
}
export function throwError() {
  throw Error("error!");
}

shisama

console.log(2 ** 53)
// 9007199254740992
console.log(2 ** 53 + 1)
// 9007199254740992
console.log(2n ** 53n + 1n)
// 9007199254740993n
console.log(2n ** 53n * 1000n)
// 9007199254740992000n

shisama

const promise1 = Promise.resolve('foo');
const promise2 = Promise.reject('bar')
const promises = [promise1, promise2];

Promise.allSettled(promises).
  then((results) => {
    for (const result of results) {
      if (result.status === 'fulfilled') console.log(result.value, 'is fulfilled');
      if (result.status === 'rejected') console.log(result.reason, 'is rejected');
    }

shisama

let regexp = /t(e)(st(\d?))/g;
let str = 'test1test2';

str.match(regexp); 
// Array ['test1', 'test2']

let array = [...str.matchAll(regexp)];

console.log(array[0]);
// Array ["test1", "e", "st1", "1"]

shisama

const label = 'test';
console.time(label);
setTimeout(() => {
  console.timeEnd(label);
}, 3000);
// 3001.732ms v12
// 3.001s v13

shisama

const january = new Date(9e8);
const spanish = new Intl.DateTimeFormat('es', { month: 'long' });
console.log(spanish.format(january))
// 'M01' v12
// 'enero` v13

shisama

// v12
const assert = require('assert');
const SomeError = class extends Error{};

try {
  // 第一引数でthrowされたエラーがSomeErrorか判定
  assert.throws(() => {throw new TypeError({})}, SomeError)
} catch (e) {
  // eはTypeError
  assert.ok(e instanceof TypeError)