var promise = new Promise(function(resolve, reject) {
// do some long running async thing…
if (/* everything turned out fine */) {
resolve("Stuff worked!");
}
else {
reject(Error("It broke"));
}
});
//usage
promise.then(
function(result) { /* handle a successful result */ },
function(error) { /* handle an error */ }
);
// make new promise ... so this object will promise us that it will hold an Asynchronous action
// some times promise resolve and some times promise get rejected
const A = new Promise((resolve, reject) => {
setTimeout(() => {
// here we pass argument if promise get resolved
resolve('Done');
// here we pass argument if promise get rejected
reject('Didn"t');
}, 3000);
});
// design handling callback function for resolve
let handleResolvedA = (massage)=>{console.log(massage)}
// design handling callback function for reject
let handleRejectedA = (massage)=>{console.log(massage)}
// do handling for both
A.then(handleResolvedA, handleRejectedA)const prom = new Promise((resolve, reject) => {
resolve('Yay!');
});
const handleSuccess = (resolvedValue) => {
console.log(resolvedValue);
};
prom.then(handleSuccess); // Prints: 'Yay!'const executorFunction = (resolve, reject) => {
if (someCondition) {
resolve('I resolved!');
} else {
reject('I rejected!');
}
}
const myFirstPromise = new Promise(executorFunction);myPromise
.then(handleResolvedA)
.then(handleResolvedB)
.then(handleResolvedC)
.catch(handleRejectedAny)
.finally(handleComplition)
let dataIsLoading = true;
promise
.then(data => {
// do something with data
})
.catch(error => {
// do something with error
})
.finally(() => {
dataIsLoading = false;
})