javascript - Does .sort function change original array?

Question

I have that code:

arr = arr.sort(function (a, b) {
    return a.time>b.time
})

Do I need to redefine arr or it is possible just to call sort function? like this:

arr.sort(function (a, b) {
    return a.time>b.time
})

Will the sort and filter functions change the original array?

Answer 1

Use slice() to sort a copy of the original array.

var arr =[{time:4},{time:3},{time:6}];

arr.sort(function (a, b) {
  return a.time-b.time;
});

will mutate the original array and returns :

[ { time: 3 }, { time: 4 }, { time: 6 } ]

and console.log(arr) returns

[ { time: 3 }, { time: 4 }, { time: 6 } ]

but

var arr =[{time:4},{time:3},{time:6}];
arr.slice().sort(function (a, b) {
  return a.time-b.time;
});

returns

[ { time: 3 }, { time: 4 }, { time: 6 } ]

but will not affect the original array.

console.log(arr) returns

[ { time: 4 }, { time: 3 }, { time: 6 } ]