what is a promise javascript api 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: what is a promise
// Promise is a special type of object that helps you work with asynchronous operations.
// Many functions will return a promise to you in situations where the value cannot be retrieved immediately.
const userCount = getUserCount();
console.log(userCount); // Promise {<pending>}
// In this case, getUserCount is the function that returns a Promise. If we try to immediately display the value of the userCount variable, we get something like Promise {<pending>}.
// This will happen because there is no data yet and we need to wait for it.