一个支持chrome、firefox的全屏插件

(function(){
    var fullScreenApi = {
            supportsFullScreen: false,
            isFullScreen: function() { return false; },
            requestFullScreen: function() {},
            cancelFullScreen: function() {},
            fullScreenEventName: '',
            prefix: ''
        },
        browserPrefixes = 'webkit moz o ms khtml'.split(' ');
    // check for native support
    if (typeof document.cancelFullScreen != 'undefined') {
        fullScreenApi.supportsFullScreen = true;
    } else {
        // check for fullscreen support by vendor prefix
        for (var i = 0, il = browserPrefixes.length; i < il; i++ ) {
            fullScreenApi.prefix = browserPrefixes[i];
            if (typeof document[fullScreenApi.prefix + 'CancelFullScreen' ] != 'undefined' ) {
                fullScreenApi.supportsFullScreen = true;
                break;
            }
        }
    }
    // update methods to do something useful
    if (fullScreenApi.supportsFullScreen) {
        fullScreenApi.fullScreenEventName = fullScreenApi.prefix + 'fullscreenchange';
        fullScreenApi.isFullScreen = function() {
            switch (this.prefix) {
                case '':
                    return document.fullScreen;
                case 'webkit':
                    return document.webkitIsFullScreen;
                default:
                    return document[this.prefix + 'FullScreen'];
            }
        }
        fullScreenApi.requestFullScreen = function(el) {
            return (this.prefix === '') ? el.requestFullScreen() : el[this.prefix + 'RequestFullScreen']();
        }
        fullScreenApi.cancelFullScreen = function(el) {
            return (this.prefix === '') ? document.cancelFullScreen() : document[this.prefix + 'CancelFullScreen']();
        }
    }
    // jQuery plugin
    if (typeof jQuery != 'undefined') {
        jQuery.fn.requestFullScreen = function() {
            return this.each(function() {
                if (fullScreenApi.supportsFullScreen) {
                    fullScreenApi.requestFullScreen(this);
                }
            });
        };
    }
    window.fullScreenApi = fullScreenApi;
})();

$(function(){
	$('#fullscreenbtn').click(function(){
		if(window.fullScreenApi.supportsFullScreen){
			window.fullScreenApi.requestFullScreen(document.getElementById('fullscreenbox'));
		}else{
			alert('就你这浏览器，基本就告别全屏功能了');
		}
	});
});

<a id="fullscreenbtn">
	<img id="fullscreenbox" style="display: block; margin-left: auto; margin-right: auto;" src="http://pic002.cnblogs.com/images/2012/277258/2012041400022949.gif" alt="" />
</a>