async-await.js

'use strict';

function square(num) {
    return new Promise(function(resolve, reject) {
        if (num > 10)
            reject('Yo error bro!');
        else
            setTimeout(function() { resolve(num * num) }, 2000);
    });
}

async function caller2(num) {
    try {
        const ans = await square(num);
        return ans;
    } catch (err) {
        console.log('Error in caller2 = ', err);
        return Promise.reject(err);
    }
}

async function caller1(num) {
    try {
        const ans = await caller2(num);
        console.log('Ans received = ', ans);
    } catch (err) {
        console.log('Error in caller1 = ', err);
    }
}

caller1(11);