javascript - Dynamically adding a SVG gradient

Question

I have this SVG container with paths. I want to edit it, so the paths' fill will be a pattern. This is my failed attempt:

I add a gradient:

$('svg defs').prepend('<linearGradient id="MyGradient"><stop offset="5%" stop-color="#F60" /><stop offset="95%" stop-color="#FF6" /></linearGradient>');

And then change the paths' fill:

$(base + ' svg path').each(function() {
    this.setAttribute('fill','url(#MyGradient)')
}

This doesn't work. What am I missing?

Answer 1

Your problem (what you are "missing") is that jQuery creates new elements in the XHTML namespace, while SVG elements must be created in the SVG namespace. You cannot use raw code in a string for SVG elements.

The simplest (no-plugins) method is to stop leaning on jQuery so much and just use simple DOM methods to create the elements. Yes, it's more verbose than just using jQuery to magically construct your elements for you...but jQuery does not work in this case.

Demo: http://jsfiddle.net/nra29/2/

createGradient($('svg')[0],'MyGradient',[
  {offset:'5%', 'stop-color':'#f60'},
  {offset:'95%','stop-color':'#ff6'}
]);
$('svg path').attr('fill','url(#MyGradient)');

// svg:   the owning <svg> element
// id:    an id="..." attribute for the gradient
// stops: an array of objects with <stop> attributes
function createGradient(svg,id,stops){
  var svgNS = svg.namespaceURI;
  var grad  = document.createElementNS(svgNS,'linearGradient');
  grad.setAttribute('id',id);
  for (var i=0;i<stops.length;i++){
    var attrs = stops[i];
    var stop = document.createElementNS(svgNS,'stop');
    for (var attr in attrs){
      if (attrs.hasOwnProperty(attr)) stop.setAttribute(attr,attrs[attr]);
    }
    grad.appendChild(stop);
  }

  var defs = svg.querySelector('defs') ||
      svg.insertBefore( document.createElementNS(svgNS,'defs'), svg.firstChild);
  return defs.appendChild(grad);
}

Using a Library

Alternatively, you can include Keith Woods' "jQuery SVG" plugin that has a lot of convenience methods for common SVG operations, including the ability to create linear gradients.