ECMAScript#

2021#

• String.prototype.replaceAll: 展示 'hello world'.replaceAll('l', 'L') // 'heLLo worLd'
• Promise.any: 返回第一个获得的 promise 或 AggregateError

try {
  const first = await Promise.any(promises);
  // Any of the promises was fulfilled.
} catch (error) {
  // All of the promises were rejected.
}

• WeakRefs: 弱引用，不会阻止垃圾回收进行
• Logical Assignment Operators: 结合逻辑运算符和赋值表达式

a ||= b
a || (a = b)

a &&= b
a && (a = b)

a ??= b
a ?? (a = b)

• Numeric separators: 1_000_000_000, 1_123_123_321.38

2020#

• String.prototype.matchAll: 结合 Array.from 使用
• import(): 动态导入
• BigInt: 9213817878187189378912737189738912n
• Promise.allSettled: 不在乎成功或失败

const promises = [fetch('index.html'), fetch('https://does-not-exist/')]

const results = await Promise.allSettled(promises);
const errors = results
  .filter(p => p.status === 'rejected') // 收集错误的回调
  .map(p => p.reason);

• globalThis: 未理解
• for-in mechanics:
• Optional Chaining: 可选链，a?.b?.c?.d, a?.b?.()
• Nullish coalescing Operator: a = b ?? 'default string' // b 为 null or undefined 时有效，对空字符串和0不作处理
• import.meta: 未理解，未实践