代碼示例：
<script type="text/javascript">
new Promise(function(resolve, reject) {
console.log(111);
resolve(222);
}).then(function(value) {
console.log(value);
return 333;
}).then(function(value) {
console.log(value);
throw "An Error";
}).catch(function(err) {
console.log(err);
}).finally(function(){
console.log("End");
});
</script>
示例代碼2：
<html>
<head>
<h2> Javascript Promise</h2>
</br>
</head>
<body>
<script>
var p = new Promise(function(resolve, reject) {
var x = 2 + 3;
if (x == 5)
resolve(" executed and resolved successfully");
else
reject("rejected");
});
p.then(function(fromResolve) {
document.write("Promise is" + fromResolve);
}).catch(function(fromReject) {
document.write("Promise is " + fromReject);
});
</script>
</body>
</html>