How to manipulate translate transforms on a SVG element with javascript in chrome?

There are two ways to get/set transform values for SVG elements in Chrome, Firefox, IE, or any standards-fearing SVG user agent:

Handling Transforms via Attributes

// Getting
var xforms = myElement.getAttribute('transform');
var parts  = /translate\(\s*([^\s,)]+)[ ,]([^\s,)]+)/.exec(xforms);
var firstX = parts[1],
    firstY = parts[2];

// Setting
myElement.setAttribute('transform','translate(30,100)');

Pros: Simple to set and understand (same as the markup).
Cons: Have to parse the string value to find what you want; for animated values, can’t ask for the base value when the animation is active; feels dirty.

Handling Transforms via SVG DOM Bindings

// Getting
var xforms = myElement.transform.baseVal; // An SVGTransformList
var firstXForm = xforms.getItem(0);       // An SVGTransform
if (firstXForm.type == SVGTransform.SVG_TRANSFORM_TRANSLATE){
  var firstX = firstXForm.matrix.e,
      firstY = firstXForm.matrix.f;
}

// Setting
myElement.transform.baseVal.getItem(0).setTranslate(30,100);

Pros: No need to try to parse strings on your own; preserves existing transform lists (you can query or tweak just a single transformation in the list); you get real values, not strings.
Cons: Can be confusing to understand at first; more verbose for setting simple values; no convenient method for extracting rotation, scale, or skew values from the SVGTransform.matrix, lack of browser support.

You may find a tool I wrote for exploring the DOM helpful in this.

1. Go to http://objjob.phrogz.net/svg/object/131
2. Click the “Show inherited properties/methods?” checkbox
3. See that the SVGRectElement has a transform property that is an SVGAnimatedTransformList.
4. Click on SVGAnimatedTransformList to see the properties and methods that object supports.
5. Explore!