Changing SVG image color with javascript

Sure, here is an example (standard HTML boilerplate omitted):

<svg id="svg1" xmlns="http://www.w3.org/2000/svg" style="width: 3.5in; height: 1in">
  <circle id="circle1" r="30" cx="34" cy="34" 
            style="fill: red; stroke: blue; stroke-width: 2"/>
  </svg>
<button onclick="circle1.style.fill='yellow';">Click to change to yellow</button>

This is for <object> SVG and className is .svgClass

<object class="svgClass" type="image/svg+xml" data="image.svg"></object>

So JavaScript code is like this:

// change to red
    document.querySelector(".svgClass").getSVGDocument().getElementById("svgInternalID").setAttribute("fill", "red")

To change svgInternalID you have to open SVG file which is plain .txt (ie image.svg) and edit it

<path id="svgInternalID"

Given some SVG:

<div id="main">
  <svg id="octocat" xmlns="http://www.w3.org/2000/svg" width="400px" height="400px" viewBox="-60 0 420 330" style="fill:#fff;stroke: #000; stroke-opacity: 0.1">
    <path id="puddle" d="m296.94 295.43c0 20.533-47.56 37.176-106.22 37.176-58.67 0-106.23-16.643-106.23-37.176s47.558-37.18 106.23-37.18c58.66 0 106.22 16.65 106.22 37.18z"/>
    <path class="shadow-legs" d="m161.85 331.22v-26.5c0-3.422-.619-6.284-1.653-8.701 6.853 5.322 7.316 18.695 7.316 18.695v17.004c6.166.481 12.534.773 19.053.861l-.172-16.92c-.944-23.13-20.769-25.961-20.769-25.961-7.245-1.645-7.137 1.991-6.409 4.34-7.108-12.122-26.158-10.556-26.158-10.556-6.611 2.357-.475 6.607-.475 6.607 10.387 3.775 11.33 15.105 11.33 15.105v23.622c5.72.98 11.71 1.79 17.94 2.4z"/>
    <path class="shadow-legs" d="m245.4 283.48s-19.053-1.566-26.16 10.559c.728-2.35.839-5.989-6.408-4.343 0 0-19.824 2.832-20.768 25.961l-.174 16.946c6.509-.025 12.876-.254 19.054-.671v-17.219s.465-13.373 7.316-18.695c-1.034 2.417-1.653 5.278-1.653 8.701v26.775c6.214-.544 12.211-1.279 17.937-2.188v-24.113s.944-11.33 11.33-15.105c0-.01 6.13-4.26-.48-6.62z"/>
    <path id="cat" d="m378.18 141.32l.28-1.389c-31.162-6.231-63.141-6.294-82.487-5.49 3.178-11.451 4.134-24.627 4.134-39.32 0-21.073-7.917-37.931-20.77-50.759 2.246-7.25 5.246-23.351-2.996-43.963 0 0-14.541-4.617-47.431 17.396-12.884-3.22-26.596-4.81-40.328-4.81-15.109 0-30.376 1.924-44.615 5.83-33.94-23.154-48.923-18.411-48.923-18.411-9.78 24.457-3.733 42.566-1.896 47.063-11.495 12.406-18.513 28.243-18.513 47.659 0 14.658 1.669 27.808 5.745 39.237-19.511-.71-50.323-.437-80.373 5.572l.276 1.389c30.231-6.046 61.237-6.256 80.629-5.522.898 2.366 1.899 4.661 3.021 6.879-19.177.618-51.922 3.062-83.303 11.915l.387 1.36c31.629-8.918 64.658-11.301 83.649-11.882 11.458 21.358 34.048 35.152 74.236 39.484-5.704 3.833-11.523 10.349-13.881 21.374-7.773 3.718-32.379 12.793-47.142-12.599 0 0-8.264-15.109-24.082-16.292 0 0-15.344-.235-1.059 9.562 0 0 10.267 4.838 17.351 23.019 0 0 9.241 31.01 53.835 21.061v32.032s-.943 11.33-11.33 15.105c0 0-6.137 4.249.475 6.606 0 0 28.792 2.361 28.792-21.238v-34.929s-1.142-13.852 5.663-18.667v57.371s-.47 13.688-7.551 18.881c0 0-4.723 8.494 5.663 6.137 0 0 19.824-2.832 20.769-25.961l.449-58.06h4.765l.453 58.06c.943 23.129 20.768 25.961 20.768 25.961 10.383 2.357 5.663-6.137 5.663-6.137-7.08-5.193-7.551-18.881-7.551-18.881v-56.876c6.801 5.296 5.663 18.171 5.663 18.171v34.929c0 23.6 28.793 21.238 28.793 21.238 6.606-2.357.474-6.606.474-6.606-10.386-3.775-11.33-15.105-11.33-15.105v-45.786c0-17.854-7.518-27.309-14.87-32.3 42.859-4.25 63.426-18.089 72.903-39.591 18.773.516 52.557 2.803 84.873 11.919l.384-1.36c-32.131-9.063-65.692-11.408-84.655-11.96.898-2.172 1.682-4.431 2.378-6.755 19.25-.80 51.38-.79 82.66 5.46z"/>
    <path id="face" d="m258.19 94.132c9.231 8.363 14.631 18.462 14.631 29.343 0 50.804-37.872 52.181-84.585 52.181-46.721 0-84.589-7.035-84.589-52.181 0-10.809 5.324-20.845 14.441-29.174 15.208-13.881 40.946-6.531 70.147-6.531 29.07-.004 54.72-7.429 69.95 6.357z"/>
    <path id="eyes" d="m160.1 126.06 c0 13.994-7.88 25.336-17.6 25.336-9.72 0-17.6-11.342-17.6-25.336 0-13.992 7.88-25.33 17.6-25.33 9.72.01 17.6 11.34 17.6 25.33z m94.43 0 c0 13.994-7.88 25.336-17.6 25.336-9.72 0-17.6-11.342-17.6-25.336 0-13.992 7.88-25.33 17.6-25.33 9.72.01 17.6 11.34 17.6 25.33z"/>
    <path id="pupils" d="m154.46 126.38 c0 9.328-5.26 16.887-11.734 16.887s-11.733-7.559-11.733-16.887c0-9.331 5.255-16.894 11.733-16.894 6.47 0 11.73 7.56 11.73 16.89z m94.42 0 c0 9.328-5.26 16.887-11.734 16.887s-11.733-7.559-11.733-16.887c0-9.331 5.255-16.894 11.733-16.894 6.47 0 11.73 7.56 11.73 16.89z"/>
    <circle id="nose" cx="188.5" cy="148.56" r="4.401"/>
    <path id="mouth" d="m178.23 159.69c-.26-.738.128-1.545.861-1.805.737-.26 1.546.128 1.805.861 1.134 3.198 4.167 5.346 7.551 5.346s6.417-2.147 7.551-5.346c.26-.738 1.067-1.121 1.805-.861s1.121 1.067.862 1.805c-1.529 4.324-5.639 7.229-10.218 7.229s-8.68-2.89-10.21-7.22z"/>
    <path id="octo" d="m80.641 179.82 c0 1.174-1.376 2.122-3.07 2.122-1.693 0-3.07-.948-3.07-2.122 0-1.175 1.377-2.127 3.07-2.127 1.694 0 3.07.95 3.07 2.13z m8.5 4.72 c0 1.174-1.376 2.122-3.07 2.122-1.693 0-3.07-.948-3.07-2.122 0-1.175 1.377-2.127 3.07-2.127 1.694 0 3.07.95 3.07 2.13z m5.193 6.14 c0 1.174-1.376 2.122-3.07 2.122-1.693 0-3.07-.948-3.07-2.122 0-1.175 1.377-2.127 3.07-2.127 1.694 0 3.07.95 3.07 2.13z m4.72 7.08 c0 1.174-1.376 2.122-3.07 2.122-1.693 0-3.07-.948-3.07-2.122 0-1.175 1.377-2.127 3.07-2.127 1.694 0 3.07.95 3.07 2.13z m5.188 6.61 c0 1.174-1.376 2.122-3.07 2.122-1.693 0-3.07-.948-3.07-2.122 0-1.175 1.377-2.127 3.07-2.127 1.694 0 3.07.95 3.07 2.13z m7.09 5.66 c0 1.174-1.376 2.122-3.07 2.122-1.693 0-3.07-.948-3.07-2.122 0-1.175 1.377-2.127 3.07-2.127 1.694 0 3.07.95 3.07 2.13z m9.91 3.78 c0 1.174-1.376 2.122-3.07 2.122-1.693 0-3.07-.948-3.07-2.122 0-1.175 1.377-2.127 3.07-2.127 1.694 0 3.07.95 3.07 2.13z m9.87 0 c0 1.174-1.376 2.122-3.07 2.122-1.693 0-3.07-.948-3.07-2.122 0-1.175 1.377-2.127 3.07-2.127 1.694 0 3.07.95 3.07 2.13z m10.01 -1.64 c0 1.174-1.376 2.122-3.07 2.122-1.693 0-3.07-.948-3.07-2.122 0-1.175 1.377-2.127 3.07-2.127 1.694 0 3.07.95 3.07 2.13z"/>
    <path id="drop" d="m69.369 186.12l-3.066 10.683s-.8 3.861 2.84 4.546c3.8-.074 3.486-3.627 3.223-4.781z"/>
  </svg>
</div>

Using jQuery, for instance, you could do:

var _currentFill = "#f00"; // red
$svg = $("#octocat");
$("#face", $svg).attr('style', "fill:"+_currentFill); })

I provided a coloring book demo as an answer to another stackoverflow question: http://bl.ocks.org/4545199. Tested on Safari, Chrome, and Firefox.

Here's a full example that shows how to modify the fill color of an svg referenced via <embed>, <object> and <iframe>.

Also see How to apply a style to an embedded SVG?

Your SVG must be inline in your document in order to be styled with CSS. This can be done by writing the SVG markup directly into your HTML code, or by using SVG injection, which replaces the img element with the content from and SVG file with Javascript.

There is an open source library called SVGInject that does this for you. All you have to do is to add the attribute onload="SVGInject(this)" to you <img> tag.

A simple example using SVGInject looks like this:

<html>
  <head>
    <script src="svg-inject.min.js"></script>
  </head>
  <body>
    <img src="image.svg" onload="SVGInject(this)" />
  </body>
</html>

After the image is loaded the onload="SVGInject(this) will trigger the injection and the <img> element will be replaced by the contents of the SVG file provided in the src attribute.