Suppose we have an array of objects like this −
const arr = [ {userId: "3t5bsFB4PJmA3oTnm", from: 1, to: 6}, {userId: "3t5bsFB4PJmA3oTnm", from: 7, to: 15}, {userId: "3t5bsFB4PJmA3oTnm", from: 172, to: 181}, {userId: "3t5bsFB4PJmA3oTnm", from: 182, to: 190} ];
We are required to write a JavaScript function that takes in one such array. The function should group overlapping objects based on their "from" and "to" property into a single object like this −
const output = [ {userId: "3t5bsFB4PJmA3oTnm", from: 1, to: 15}, {userId: "3t5bsFB4PJmA3oTnm", from: 172, to: 190} ];
Example
const arr = [ {userId: "3t5bsFB4PJmA3oTnm", from: 1, to: 6}, {userId: "3t5bsFB4PJmA3oTnm", from: 7, to: 15}, {userId: "3t5bsFB4PJmA3oTnm", from: 172, to: 181}, {userId: "3t5bsFB4PJmA3oTnm", from: 182, to: 190} ]; const groupByDuration = (arr = []) => { const result = arr.reduce((acc, val) => { let last = acc[acc.length - 1] || {}; if (last.userId === val.userId && last.to + 1 === val.from) { last.to = val.to; } else { acc.push({ userId: val.userId, from: val.from, to: val.to }); } return acc; }, []); return result; } console.log(groupByDuration(arr));
Output
And the output in the console will be −
[ { userId: '3t5bsFB4PJmA3oTnm', from: 1, to: 15 }, { userId: '3t5bsFB4PJmA3oTnm', from: 172, to: 190 } ]