这8个JS 新功能，你应该去尝试一下

lat arr=[1,2,3,4,5]

arr[1] //2

arr[4] // 5

arr[arr.length-1]

arr.at(-1) //5 arr.at(-2) //4

if (Object.prototype.hasOwnProperty.call(object, "fn")) { console.log('有') }

if (Object.hasOwn(object, "fn")) { console.log("有") }

class Person{ name = '小芳'; #age = 16; consoleAge(){ console.log(this.#age) } } const person = new Person(); console.log(person.name); //小芳 console.log(button.#value); //报错 button.#value = false;//报错

class C { #brand; #method() {} get #getter() {} static isC(obj) { return #brand in obj && #method in obj && #getter in obj; } }

const strings = await import(`/i18n/${navigator.language}`);

const connection = await dbConnector();

let jQuery; try { jQuery = await import('https://cdn-a.com/jQuery'); } catch { jQuery = await import('https://cdn-b.com/jQuery'); }

const str = 'The question is TO BE, or not to be, that is to be.'; const regex = /to be/gd; const matches = [...str.matchAll(regex)]; matches[0];

async function doJob() { const rawResource = await fetch('//domain/resource-a') .catch(err => { throw new Error('Download raw resource failed', { cause: err }); }); const jobResult = doComputationalHeavyJob(rawResource); await fetch('//domain/upload', { method: 'POST', body: jobResult }) .catch(err => { throw new Error('Upload job result failed', { cause: err }); }); } try { await doJob(); } catch (e) { console.log(e); console.log('Caused by', e.cause); } // Error: Upload job result failed // Caused by TypeError: Failed to fetch

// without static blocks: class C { static x = ...; static y; static z; } try { const obj = doSomethingWith(C.x); C.y = obj.y C.z = obj.z; } catch { C.y = ...; C.z = ...; }

class C { static x = ...; static y; static z; static { try { const obj = doSomethingWith(this.x); this.y = obj.y; this.z = obj.z; } catch { this.y = ...; this.z = ...; } } }