promp node js
const readline = require("readline");
const rl = readline.createInterface({
input: process.stdin,
output: process.stdout
});
rl.question("What is your name ? ", function saveInput(name) {
console.log(`His name is ${name}`);
rl.close();
});
rl.on("close", function saveInput() {
console.log("\nBYE BYE !!!");
process.exit(0);
});js create a promise
/*
A Promise is a proxy for a value not necessarily known when the promise is created.
It allows you to associate handlers with an asynchronous action's eventual success
value or failure reason.
*/
let promise = new Promise((resolve , reject) => {
fetch("https://myAPI")
.then((res) => {
// successfully got data
resolve(res);
})
.catch((err) => {
// an error occured
reject(err);
});
});javascript return promise
function doSomething() {
return new Promise((resolve, reject) => {
console.log("It is done.");
// Succeed half of the time.
if (Math.random() > .5) {
resolve("SUCCESS")
} else {
reject("FAILURE")
}
})
}
const promise = doSomething();
promise.then(successCallback, failureCallback);promise
new Promise( (res, rej) => {
setTimeout(() => res(1), 1000);
}).then( (res) => {
console.log(res); // 1
return res*2
}).then( (res) => {
console.log(res); // 2
});promise catch
//create a Promise
var p1 = new Promise(function(resolve, reject) {
resolve("Success");
});
//Execute the body of the promise which call resolve
//So it execute then, inside then there's a throw
//that get capture by catch
p1.then(function(value) {
console.log(value); // "Success!"
throw "oh, no!";
}).catch(function(e) {
console.log(e); // "oh, no!"
});Promise
let doSecond = () => {
console.log('Do second.')
}
let doFirst = new Promise((resolve, reject) => {
setTimeout(() => {
console.log('Do first.')
resolve()
}, 500)
})
doFirst.then(doSecond)Copyright © 2021 Codeinu
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