Immutability!

README.md

@@ -193,11 +193,11 @@ Note that the order of transformations matters! The translate must be applied be
 
 <a href="#transform_scale" name="transform_scale">#</a> <i>transform</i>.<b>scale</b>(<i>k</i>)
 
-Returns a new transform, multiplying this transform’s scale *k₀* by the specified number *k*. The returned transform’s scale is equal to *k₀* × *k*.
+Returns a transform whose scale *k₁* is equal to *k₀* × *k*, where *k₀* is this transform’s scale.
 
 <a href="#transform_translate" name="transform_translate">#</a> <i>transform</i>.<b>translate</b>(<i>x</i>, <i>y</i>)
 
-Returns a new transform, incrementing this transform’s translation *t<sub>x0</sub>* and *t<sub>y0</sub>* by the specified numbers *x* and *y*, respectively. The returned transform’s translation is equal to *t<sub>x0</sub>* + *x* and *t<sub>y0</sub>* + *y*.
+Returns a transform whose translation *t<sub>x1</sub>* and *t<sub>y1</sub>* is equal to *t<sub>x0</sub>* + *x* and *t<sub>y0</sub>* + *y*, where *t<sub>x0</sub>* and *t<sub>y0</sub>* is this transform’s translation.
 
 <a href="#transform_apply" name="transform_apply">#</a> <i>transform</i>.<b>apply</b>(<i>point</i>)
 

src/transform.js

@@ -7,10 +7,10 @@ export function Transform(k, x, y) {
 Transform.prototype = {
   constructor: Transform,
   scale: function(k) {
-    return new Transform(this.k * k, this.x, this.y);
+    return k === 1 ? this : new Transform(this.k * k, this.x, this.y);
   },
   translate: function(x, y) {
-    return new Transform(this.k, this.x + this.k * x, this.y + this.k * y);
+    return x === 0 & y === 0 ? this : new Transform(this.k, this.x + this.k * x, this.y + this.k * y);
   },
   apply: function(point) {
     return [point[0] * this.k + this.x, point[1] * this.k + this.y];