/*
var p = new Promise(function(resolve, reject) {
console.log("create a promise");
resolve("success");
});
console.log("after new Promise");
p.then(function(value) {
console.log(value);
});
//xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Promise.resolve(11)
.then((res) => {
console.log(res)
return 2
})
.catch((err) => {
return 3
})
.then((res) => {
console.log("res")
})
//xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
function taskA() {
console.log("Task A");
}
function taskB() {
console.log("Task B");
}
function onRejected(error) {
console.log("Catch Error: A or B", error);
}
var promise = Promise.resolve();
promise
.then(taskA)
.then(taskB)
.catch(onRejected) // 捕获前面then方法中的异常
//xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
let p = new Promise(function (resolve, reject) {
resolve("蚂蚁部落");
})
p.then(function (val) {
console.log(val)
})
//xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
let p = new Promise(function(resolve, reject) {
console.log("蚂蚁部落一");
resolve("蚂蚁部落二");
})
p.then(function(val) {
console.log(val)
})
console.log("蚂蚁部落三");
//xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
setTimeout(function(){
console.log("index");
},0);
console.log("蚂蚁部落");
//xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
let p = new Promise(function(resolve, reject) {
resolve("蚂蚁部落");
});
p.then(function(value) {
console.log(value);
return value + "前端";
}).then(function(value) {
console.log(value);
});
//xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
const promises = [
Promise.resolve('a'),
Promise.resolve('b'),
Promise.resolve('c'),
];
Promise.all(promises)
.then((arr) =>
console.log(arr)
);
//xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
function timesTwoAsync(x) {
return new Promise(resolve => resolve(x * 3));
}
const arr = [1, 2, 3];
const promiseArr = arr.map(timesTwoAsync);
Promise.all(promiseArr)
.then(result => {
console.log(result)
}
);
//xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
const urls = [
'http://example.com/first.txt',
'http://example.com/second.txt',
];
const promises = urls.map(
url => downloadText(url)
);
Promise.all(promises)
.then(result => {
console.log(result)
}
);
//xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
function putDookieInAnyArray(arr) {
return [...arr, 'dookie'];
}
const result = putDookieInAnyArray(['I', 'really', "don't", 'like']);
console.log(result)
// ["I", "really", "don't", "like", "dookie"]
const person = {
name: 'Todd',
age: 29,
};
const copyOfTodd = { ...person };
console.log(copyOfTodd)
*/
promise小练习
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