promise-example.js

function asyncFunc() {
    return new Promise((resolve, reject) => {
        setTimeout(() => {
          const result = Math.random();
          result > 0.5 ? resolve(result) : reject('Oppps....I cannot calculate')
        }, 1)
    });
}

for (let i=0; i<10; i++) {
	asyncFunc()
    	.then(result => console.log('Result is: ' + result))
    	.catch(result => console.log('Error: ' + result))
}

promise-output.txt

Result is: 0.7930997430022211 
Error: Oppps....I cannot calculate 
Result is: 0.6412258210597288 
Result is: 0.7890325910244533 
Error: Oppps....I cannot calculate 
Error: Oppps....I cannot calculate 
Result is: 0.8619834683310168 
Error: Oppps....I cannot calculate 
Error: Oppps....I cannot calculate 
Result is: 0.8258410427354488