By Opera Software

From Opera 15 onward, Opera 11 & 12’s extension format is no longer supported, and instead, we’ve switched to Chromium’s extension model. Check out our new documentation for developing extensions for Opera 15 and higher and start building your own extensions.


The background color for the badge; accepts hexadecimal notation, RGBA, and color name values (e.g., #afafaf, (200, 200, 200, 0), blue).


// The background process (index.html)

// Set the button's properties
var properties = {
  disabled: false,
  title: "My Test Extension",
  icon: "icon.18x18.png",
  badge: {
    backgroundColor: 'blue',
    color: '#ffffff',
    textContent: '42'

// Add the button to the browser UI
var button = opera.contexts.toolbar.createItem(properties);

// Change the background color of the badge with each button click
var i = 1;
button.addEventListener('click', handleClick, false);

function handleClick() {
  var badgeColor = (i % 2) ? '#5566ff' : '#cc5555';
  button.badge.backgroundColor = badgeColor;

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