ES6 - Promise

How to create a Promise in javascript

Promise creation is using new operator with Promise Constructor. Promise constructor contains resolve and reject that are functions.

const promise = new Promise((resolve, reject) => {

});

Here is an example

const promise = new Promise((resolve, reject) => {
    resolve("hello");
});
promise.then((res) => {
    console.log("then function called",res);
});
promise.catch((err) => {
        console.log("catch function called");

});

const promise = new Promise((resolve, reject) => {
    reject(new Error("Error message"));
});
promise.then((res) => {
    console.log("then function called",res);
});
promise.catch((err) => {
        console.log("catch function called");

});