then function in javascript code example
Example 1: promise catch
var p1 = new Promise(function(resolve, reject) {
resolve("Success");
});
p1.then(function(value) {
console.log(value);
throw "oh, no!";
}).catch(function(e) {
console.log(e);
});
Example 2: js return a promise
function myAsyncFunction(url) {
return new Promise((resolve, reject) => {
const xhr = new XMLHttpRequest();
xhr.open("GET", url);
xhr.onload = () => resolve(xhr.responseText);
xhr.onerror = () => reject(xhr.statusText);
xhr.send();
});
}
Example 3: .then javascript
const promise2 = doSomething().then(successCallback, failureCallback);