Async & Await Example

// output "A" after a random time between 0 & 3 seconds
function outputA(){
    
    var randomTime = Math.floor(Math.random() * 3000) + 1;

    return new Promise(function(resolve, reject){
        setTimeout(function(){
            console.log("A");
            resolve("outputA() complete");
        },randomTime);
    });   
}

// output "B" after a random time between 0 & 3 seconds
function outputB(){

    var randomTime = Math.floor(Math.random() * 3000) + 1;

    return new Promise(function(resolve, reject){
        setTimeout(function(){
            console.log("B");
           resolve("outputB() complete");
        },randomTime);
    });   
}

// output "C" after a random time between 0 & 3 seconds
function outputC(){

    var randomTime = Math.floor(Math.random() * 3000) + 1;

    return new Promise(function(resolve, reject){
        setTimeout(function(){
            console.log("C");
            resolve("outputC() complete");
        },randomTime);
    });   
}

// invoke the functions using then and catch

function ABC_then_catch(){
    outputA()
    .then(outputB)
    .then(outputC)
    .then(outputCMsg => console.log(outputCMsg))
    .catch(rejectMsg => console.log(rejectMsg));
}

// invoke the functions using async and await

async function ABC_async_await(){
    try{
        await outputA();
        await outputB();
        var outputCMsg = await outputC();
        console.log(outputCMsg);
    }catch(rejectMsg){
        console.log(rejectMsg)
    }
}

// Uncomment each function to see how it behaves

//ABC_then_catch();
//ABC_async_await();