Sort array of objects

let _ = require('lodash'); let arr = [ { id: 1, index: 0, }, { id: 2, index: 1, position: 0, }, { id: 3, index: 2, } ]; let sortFn = (o) => { if(o.position === undefined) return o.index; return o.position; }; let result = _.sortBy(arr, sortFn) .map(o => o.id) // Expected result: id: 2, 1, 3 console.log(result); let arr2 = [ { id: 1, index: 0, position: 2, }, { id: 2, index: 1, position: 0, }, { id: 3, index: 2, } ]; let result2 = _.sortBy(arr2, sortFn) .map(o => o.id) // Expected result: id: 2, 3, 1 console.log(result2);