JavaScript Scope All In One

[xgqfrms]

JavaScript Scope All In One

Global Scope / 全局作用域 Script Scope / 脚本作用域 Local Scope / 局部作用域 (函数作用域) Block Scope / 块级作用域 ( { } 作用域) Catch Block Scope / 捕获块级作用域 ( try...catch 作用域) Closure Scope / 闭包作用域

7. Promise Scope ???

// 1. Global Scope / 全局作用域
var a = 1;
// 2. Script Scope / 脚本作用域
let b = 2;
// 3. Local Scope / 局部作用域 (函数作用域)
(function(){
  var bb = 2;
  // ???
  let c = 3;
})();
// ES6 let 等价于 ES5 IIFE ???

// 4. Block Scope / 块级作用域 ( `{ }` 作用域)
for (const item of ['block']) {
  var a1 = item;
  let b1 = item;
  const c1 = item;
  console.log(`a1,b1,c1 =`, a1,b1,c1);
}

// 5. Catch Scope / 捕获作用域 ( `try...catch` 作用域)
try {
  throw new Error(`catch scope ❌`);
} catch (error) {
  let err = error;
  console.error(`err =`, err);
}

// 6. Promise Scope ???
Promise.resolve(() => {
  var p1 = 1;
  let p2 = 2;
  const p3 = 3;
  console.log(`p1,p2,p3 =`, p1,p2,p3);
});

new Promise((resolve, reject) => {
  resolve(`200 ✅`);
}).then(res => {
  var pRes = res;
  console.log(`pRes`, pRes);
}, err => {
  var pErr = err;
  console.log(`pErr`, pErr);
}).catch(err => {
  var cRrr = err;
  console.log(`cRrr`, cRrr);
}).finally(() => {
  var loading = false;
  console.log(`loading`, loading);
});

new Promise((resolve, reject) => {
  reject(`404 ❌`);
}).then(res => {
  var pRes = res;
  console.log(`pRes`, pRes);
}, err => {
  var pErr = err;
  console.log(`pErr`, pErr);
}).catch(err => {
  var cRrr = err;
  console.log(`cRrr`, cRrr);
}).finally(() => {
  var loading = false;
  console.log(`loading`, loading);
});

[xgqfrms]

https://www.cnblogs.com/xgqfrms/p/17239483.html