JavaScriptCollection
diff --git a/‎d3.js‎
Lines changed: 4 additions & 2 deletions b/‎d3.js‎
Lines changed: 4 additions & 2 deletions
@@ -4285,9 +4285,11 @@ d3 = function() {
   }
   d3.geom.polygon = function(coordinates) {
     coordinates.area = function() {
-      var i = 0, n = coordinates.length, area = coordinates[n - 1][1] * coordinates[0][0] - coordinates[n - 1][0] * coordinates[0][1];
+      var i = -1, n = coordinates.length, a, b = coordinates[n - 1], area = 0;
       while (++i < n) {
-        area += coordinates[i - 1][1] * coordinates[i][0] - coordinates[i - 1][0] * coordinates[i][1];
+        a = b;
+        b = coordinates[i];
+        area += a[1] * b[0] - a[0] * b[1];
       }
       return area * .5;
     };
Original file line number	Diff line number	Diff line change
`@@ -4285,9 +4285,11 @@ d3 = function() {`
`4285`	`4285`	`}`
`4286`	`4286`	`d3.geom.polygon = function(coordinates) {`
`4287`	`4287`	`coordinates.area = function() {`
`4288`		`- var i = 0, n = coordinates.length, area = coordinates[n - 1][1] * coordinates[0][0] - coordinates[n - 1][0] * coordinates[0][1];`
	`4288`	`+ var i = -1, n = coordinates.length, a, b = coordinates[n - 1], area = 0;`
`4289`	`4289`	`while (++i < n) {`
`4290`		`- area += coordinates[i - 1][1] * coordinates[i][0] - coordinates[i - 1][0] * coordinates[i][1];`
	`4290`	`+ a = b;`
	`4291`	`+ b = coordinates[i];`
	`4292`	`+ area += a[1] * b[0] - a[0] * b[1];`
`4291`	`4293`	`}`
`4292`	`4294`	`return area * .5;`
`4293`	`4295`	`};`