Here's my way using if statements.
const converTime = (time) => {_x000D_
let hour = (time.split(':'))[0]_x000D_
let min = (time.split(':'))[1]_x000D_
let part = hour > 12 ? 'pm' : 'am';_x000D_
_x000D_
min = (min+'').length == 1 ? `0${min}` : min;_x000D_
hour = hour > 12 ? hour - 12 : hour;_x000D_
hour = (hour+'').length == 1 ? `0${hour}` : hour;_x000D_
_x000D_
return (`${hour}:${min} ${part}`)_x000D_
}_x000D_
_x000D_
console.log(converTime('18:00:00'))_x000D_
console.log(converTime('6:5:00'))
_x000D_