Promises example

promises.js

// java script is asynchronous
// it is not synchronous
// it is asynchronous
// it is not blocking

// const a = ""
// const a = 0
// const a = {}
// const a = []
// const a = [""]
// const a = [0]
// const a = () => {}
// function a(){}

// how to declare a promise
// new Promise() means initializing a promiseObj object
// = means assigning a value to a promiseObj object
// const promiseObj = new Promise((resolve, reject) => {
//     // generate a random 2 digit positive integer
//     const randomNum = Math.floor(Math.random() * 100)

//     console.log(randomNum, "randomNum");
//     if (randomNum % 2 === 0) {
//         resolve(randomNum)
//     }
//     else {
//         reject("Promise is rejected, putin")
//     }
// })

// promiseObj.then((res) => {
//     console.log(res, "Promise is resolved");
// }).catch((err) => {
//     console.error(err);
// })
const promiseObj = () => new Promise((resolve, reject) => {
    // generate a random 2 digit positive integer
    const randomNum = Math.floor(Math.random() * 100)

    if (randomNum % 2 === 0) {
        resolve(randomNum + " is even")
    }
    else {
        reject(randomNum + " Promise is rejected, putin")
    }
})

async function main() {
    console.log("Start");

    try {
        const res = await promiseObj()
        console.log(res, "Promise is resolved");
    } catch (error) {
        console.error(error);
    }


    console.log("end of program");
}

main()