17-promises.html

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>introduction to promises</title>
</head>

<body>
    <script>
        // the solution of the callback is promiswes. we use promises in javaScript because it will done our work easy 


        let promises1 = new Promise((resolve, reject)=>{
            setTimeout(() => {
                //console.log("hello this is alert promises resolve");
                resolve(true)
            }, 5000);
        })

        promises1.then(alert)


        let promises2 = new Promise((resolve, reject) => {
            setTimeout(() => {
                //  console.log("this is reject promise")
                reject(new Error("i am an error"))
            }, 5000)
        });


        // promises1.then(function value(v1){
        //     console.log(v1)
        // })

        //also write with this 
        // to get the value 
        promises1.then((value) => {
            console.log(value);
        })

        // to catch the error
        promises2.catch((error) => {
            console.log("occure some error")
        })

        //also you can give both at a time 

        promises2.then((value)=>{
            console.log(value);
        },(error)=>{
            console.log("some error occure ")
        });


    </script>
</body>

</html>