In this tutorial, we will learn how to write a function in JavaScript Promise with examples. In this, we use mainly resolve or reject.
JavaScript Promise
- A JavaScript Promise is used for reject or resolve the statement.
- JavaScript Promise use the then(), catch() methods mainly.
- For this we can take the constant values also
JavaScript Promise States:
- Pending
- Resolve
- Rejected
Promises have the Main Methods :
- ‘then()’
- ‘catch()’
JavaScript Promise Example
<html>
<head>
<title>Promise Example</title>
<script>
let promise = new Promise(function (resolve, reject) {
const x = "English";
const y = "Maths"
if (x === y) {
resolve();
} else {
reject();
}
});
promise.
then(function () {
console.log('Success, You are a Promise');
}).
catch(function () {
console.log('Some error has occurred');
});
</script>
</head>
<body>
</body>
</html>
Output:
Some error has occurred