Returning an array from a function with JavaScript. Reversing the order of the returned array

Question

//draw the points
//var pointOrigins1=new Array();
//pointOrigins1 = drawPoints(canvas, context);
//var pointOrigins2=new Array();
//pointOrigins2 = pointOrigins1;
//pointOrigins2.reverse();
//Place a donut on each point origin
//circlePointOrigins(canvas,context,pointOrigins1);
console.log(drawPoints(canvas, context));

//console.log(pointOrigins1);
//console.log(pointOrigins2);

//renderCheckers(canvas,context,pointOrigins1,pointOrigins2,checkers1,checkers2,initiator);





function drawPoints(canvas,context) {
    pointOrigins.push(drawTriangle(50+i,550,false,'black',canvas,context));
    return pointOrigins;
}

The code below is run. In the above code I have commented out what I have been trying that is not working yet. My goal is to reverse the returned array that is returned from the drawPoints function:

console.log(drawPoints(canvas, context));

Runs and the output looks like in the console:

[Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object, Object]

I'm noticing that in the render event of gameview if I call:

var pointOrigins1=new Array();
pointOrigins1 = drawPoints(canvas, context);
var pointOrigins2=new Array();
pointOrigins2 = pointOrigins1;
pointOrigins2.reverse();

the reverse has no effect at all. I intend to use the .reverse function for use with JavaScript arrays but right now that is not working.

I'm not sure how to resolve the .reverse problem yet but I think it might have something to do with how I am returning my functions.

Thank you for posting....

Answer 1

Array.prototype.reverse modifies the array it's given. In your example both pointOrigins2 and pointOrigins1 end up containing the same reversed array. Try changing the lines

var pointOrigins2=new Array();
pointOrigins2 = pointOrigins1;

to

var pointOrigins2=pointOrigins1.slice();

Answer 2

Here is another way to reverse an array using this function! Hope it helps!

var reverseArray = function(InputArray){
  for(i=0; i<= Math.floor((InputArray.length / 2) -1); i++){
    var a = InputArray[i];
    var b = InputArray[(InputArray.length -1) - i];
    InputArray[(InputArray.length -1) - i] = a;
    InputArray[i] = b;
  }
  return InputArray;
}