[object promise] js code example
Example 1: javascript promise
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 */ }
);
Example 2: promise javascript
const promiseA = new Promise( (resolutionFunc,rejectionFunc) => {
resolutionFunc(777);
});
// At this point, "promiseA" is already settled.
promiseA.then( (val) => console.log("asynchronous logging has val:",val) );
console.log("immediate logging");
// produces output in this order:
// immediate logging
// asynchronous logging has val: 777
Example 3: promise js
//example
function tetheredGetNumber(resolve, reject) {
try {
setTimeout(
function() {
const randomInt = Date.now();
const value = randomInt % 10;
try {
if(value >= THRESHOLD_A) {
throw new Error(`Too large: ${value}`);
}
} catch(msg) {
reject(`Error in callback ${msg}`);
}
resolve(value);
return;
}, 500);
} catch(err) {
reject(`Error during setup: ${err}`);
}
return;
}
Example 4: javascript promises
firstRequest()
.then(function(response) {
return secondRequest(response);
}).then(function(nextResponse) {
return thirdRequest(nextResponse);
}).then(function(finalResponse) {
console.log('Final response: ' + finalResponse);
}).catch(failureCallback);