I have an array of objects and need to create a new array which contains the values of a specific key within the objects. Is there a more elegant way than the following code (note: without using anything more than JQuery). Expected result is: 455, 387, 495
var arr=[{sid:387,rank:2},{sid:455,rank:1},{sid:364,rank:4},{sid:495,rank:3}];
var topThreeTemp = arr.filter(function(a){return a.rank<4;}).sort(function(a,b){return a.rank>b.rank;});
var topThreeSIDs=[];
for(var i=0;i<topThreeTemp.length;i++){
topThreeSIDs.push(topThreeTemp[i].sid);
}
console.log(topThreeSIDs.join(", "));
Use ES6 map
, instead of for
and ES6 arrow functions (syntax sugars):
const arr = [ { sid: 387,rank: 2 }, { sid: 455,rank: 1 }, { sid: 364,rank: 4 }, { sid: 495,rank: 3 } ] const topThreeSIDs = arr .filter(({ rank }) => rank < 4) .sort((a, b) => a.rank > b.rank) .map(({ sid }) => sid) console.log(topThreeSIDs.join(', '))
You could filter, sort with delta, slice and map sid
as result array.
var array = [{ sid: 387, rank: 2 }, { sid: 455, rank: 1 }, { sid: 364, rank: 4 }, { sid: 495, rank: 3 }], top3 = array .filter(({ rank }) => rank < 4) .sort((a, b) => a.rank - b.rank) .slice(0, 3) .map(({ sid }) => sid); console.log(top3.join(", "));
Use Array.map
var arr=[{sid:387,rank:2},{sid:455,rank:1},{sid:364,rank:4},{sid:495,rank:3}]; var result = arr.filter(({rank}) => rank < 4).sort((a,b) => a.rank > b.rank).map(({sid}) => sid); console.log(result.join(", "));
function pluck(objs, name, condition) {
var sol = [];
for (var i in objs) {
if (objs[i].hasOwnProperty(name) && condition && condition(objs[i])) {
// console.log(objs[i][name]);
sol.push(objs[i][name]);
}
}
return sol;
}
var arr = [{sid: 387, rank: 2}, {sid: 455, rank: 1}, {sid: 364, rank: 4}, {sid: 495, rank: 3}];
var pluckedArray = pluck(arr, sid, function (item) {
return item.rand < 4; // your custom condition
})
How about iterate the array only once, and build the resultant array?
arr.reduce((r, {rank, sid})=>(rank < 4 && (r[rank -1] = sid), r), [])
var arr = [{ sid: 387, rank: 2 }, { sid: 455, rank: 1 }, { sid: 364, rank: 4 }, { sid: 495, rank: 3 }], top3 = arr.reduce((r, {rank, sid})=>(rank < 4 && (r[rank -1] = sid), r), []); console.log(top3);
Note: When you need top 3 within highest rank 4
and also know ranks are unique, you can use this. If ranks are not unique you can use r.splice(rank-1, 0, sid)
instead of r[rank-1] = sid
and slice
top 3 at the end.
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