[removed] How can I swap elements of an array of objects (by reference, not index)?

Question

I have an array of objects a=[ {v:0}, {v:1}, {v:2}, {v:3} ] ;

I do not have the index into the array, but I do have references to

Answer 1

Here's an utility function:

function swap(list, a, b) {
  var copy = list.slice();

  copy[list.indexOf(a)] = b;
  copy[list.indexOf(b)] = a;
  
  return copy;
}

// usage
var a =[ {v:0}, {v:1}, {v:2}, {v:3} ] ;

var result = swap(a, a[1], a[3]);

console.log(result); 
// [ {v:0}, {v:3}, {v:2}, {v:1} ]

Keep in mind, since you are using Objects in your array, you need the exact reference to this value. E.g. this will not work:

var a =[ {v:0}, {v:1}, {v:2}, {v:3} ] ;

var result = swap(a, {v:1}, {v:3});

console.log(result); 
// [ {v:0}, {v:1}, {v:2}, {v:3} ]

Here's an alternative version which checks for all values in an Array:

function swap(list, a, b) {
  return list.map(function(item) {
    if (item === a) {
      return b;
    } else if (item === b) {
      return a;
    }

    return item;
  });
}