A collection of useful functions and snippets gathered from current and past projects, many of which I often re use.

reusable_functions.js

// Utilities
//---------------------------

// check if a function already exists
function function_exists (func_name) {
	if (typeof func_name === 'string') {
		func_name = this.window[func_name];
	}
	return typeof func_name === 'function';
}

// Load a script asynchronously in head
function loadScriptAsync($url) {
	var e = document.createElement('script');
	e.type="text/javascript"; e.async = true;
	e.src = $url.toString();
	document.getElementsByTagName('head')[0].appendChild(e);
}



// Layout and FX
//---------------------------

// Toggle Inner HTML
$.fn.toggleHTML = function(a, b) {
    this.html(function(_, html) {
        return $.trim(html) === a ? b : a;
    });
}

// scroll page to specified element on click
function clickScroll(target, destination) {
	$(target).on('click', function(e) {
		e.preventDefault();
    		var destination = $(destination).offset().top;
    		$('html, body').animate({
        		scrollTop: destination
   		 });
	});
}

// slide fade toggle fx - Chris Coyier
$.fn.slideFadeToggle  = function(speed, easing, callback) {
        return this.animate({opacity: 'toggle', height: 'toggle'}, speed, easing, callback);
};

// Set Height according to width
function squareIt(selector) {
	$(selector).each(function() {
		var current = $(this);
		var thisWidth = current.outerWidth();
		current.css( 'height', thisWidth );
		current.parent().css( 'height', thisWidth );
	});
}

//Equal Heights script from Chris Coyier
function equalblocks(item) {
    var currentTallest = 0,
    currentRowStart = 0,
    rowDivs = new Array(),
    $el,
    topPosition = 0;

    jQuery(item).each(function() {

        $el = jQuery(this);
        topPostion = $el.position().top;

        if (currentRowStart != topPostion) {

            // we just came to a new row.  Set all the heights on the completed row
            for (currentDiv = 0 ; currentDiv < rowDivs.length ; currentDiv++) {
                rowDivs[currentDiv].height(currentTallest);
            }

            // set the variables for the new row
            rowDivs.length = 0; // empty the array
            currentRowStart = topPostion;
            currentTallest = $el.height();
            rowDivs.push($el);

        } else {

            // another div on the current row.  Add it to the list and check if it's taller
            rowDivs.push($el);
                currentTallest = (currentTallest < $el.height()) ? ($el.height()) : (currentTallest);

            }

            // do the last row
            for (currentDiv = 0 ; currentDiv < rowDivs.length ; currentDiv++) {
                rowDivs[currentDiv].height(currentTallest);
            }

    });

}


// Ticker - used often for testimonials - NB - will require some basic CSS to work correctly
    function bangingTicker(container,element) {

        // store the container
        var tickContainer = $(container);

        // Set the height of the container
        var maxH = 0;
        tickContainer.find(element).each(function() {
        	if ( $(this).outerHeight() > maxH ) {
        		maxH = $(this).outerHeight();
        	}
        });

        tickContainer.height(maxH + 36);

        /* wrap the original tick function in a
        callback function to the fadeIn*/
        tickContainer.animate({opacity:1}).fadeIn(1000, function(){

            function tick()     {
                // get the elements on each pass
                var tickElem = tickContainer.children(element);

                // fadeout the current item
                tickElem.eq(1).siblings().animate({
                    opacity: 0
                },800, function() {

                    // rotating the elements
                    tickElem.first().appendTo(tickContainer);

                    // Show the first Element
                    tickElem.eq(1).delay(200).animate({
                        opacity: 1
                    },400);
                });

            } // end tick

            /* run the function once to avoid waiting
            for the interval on the first animation*/
            tick();

            // run the function at a set interval
            setInterval(function(){ tick() }, 8950);

        }); // end container fade in

    }


// Minified Utility Scripts
//---------------------------

// SmartResise - Paul Irish
 !function(a,b){var c=function(a,b,c){var d;return function(){function g(){c||a.apply(e,f),d=null}var e=this,f=arguments;d?clearTimeout(d):c&&a.apply(e,f),d=setTimeout(g,b||100)}};jQuery.fn[b]=function(a){return a?this.bind("resize",c(a)):this.trigger(b)}}(jQuery,"smartresize");

$(window).smartresize(function() {
	// stuff goes here	
});

/*!
 * imagesLoaded PACKAGED v3.0.4 - DeSandro
 */
(function(){"use strict";function e(){}function t(e,t){for(var n=e.length;n--;)if(e[n].listener===t)return n;return-1}var n=e.prototype;n.getListeners=function(e){var t,n,i=this._getEvents();if("object"==typeof e){t={};for(n in i)i.hasOwnProperty(n)&&e.test(n)&&(t[n]=i[n])}else t=i[e]||(i[e]=[]);return t},n.flattenListeners=function(e){var t,n=[];for(t=0;e.length>t;t+=1)n.push(e[t].listener);return n},n.getListenersAsObject=function(e){var t,n=this.getListeners(e);return n instanceof Array&&(t={},t[e]=n),t||n},n.addListener=function(e,n){var i,r=this.getListenersAsObject(e),o="object"==typeof n;for(i in r)r.hasOwnProperty(i)&&-1===t(r[i],n)&&r[i].push(o?n:{listener:n,once:!1});return this},n.on=n.addListener,n.addOnceListener=function(e,t){return this.addListener(e,{listener:t,once:!0})},n.once=n.addOnceListener,n.defineEvent=function(e){return this.getListeners(e),this},n.defineEvents=function(e){for(var t=0;e.length>t;t+=1)this.defineEvent(e[t]);return 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n=e.event;n.target=n.target||n.srcElement,i.call(t,n)},t.attachEvent("on"+n,t[n+i])});var i=function(){};t.removeEventListener?i=function(e,t,n){e.removeEventListener(t,n,!1)}:t.detachEvent&&(i=function(e,t,n){e.detachEvent("on"+t,e[t+n]);try{delete e[t+n]}catch(i){e[t+n]=void 0}});var r={bind:n,unbind:i};"function"==typeof define&&define.amd?define(r):e.eventie=r}(this),function(e){"use strict";function t(e,t){for(var n in t)e[n]=t[n];return e}function n(e){return"[object Array]"===c.call(e)}function i(e){var t=[];if(n(e))t=e;else if("number"==typeof e.length)for(var i=0,r=e.length;r>i;i++)t.push(e[i]);else t.push(e);return t}function r(e,n){function r(e,n,s){if(!(this instanceof r))return new r(e,n);"string"==typeof e&&(e=document.querySelectorAll(e)),this.elements=i(e),this.options=t({},this.options),"function"==typeof n?s=n:t(this.options,n),s&&this.on("always",s),this.getImages(),o&&(this.jqDeferred=new o.Deferred);var a=this;setTimeout(function(){a.check()})}function c(e){this.img=e}r.prototype=new e,r.prototype.options={},r.prototype.getImages=function(){this.images=[];for(var e=0,t=this.elements.length;t>e;e++){var n=this.elements[e];"IMG"===n.nodeName&&this.addImage(n);for(var i=n.querySelectorAll("img"),r=0,o=i.length;o>r;r++){var s=i[r];this.addImage(s)}}},r.prototype.addImage=function(e){var t=new c(e);this.images.push(t)},r.prototype.check=function(){function e(e,r){return t.options.debug&&a&&s.log("confirm",e,r),t.progress(e),n++,n===i&&t.complete(),!0}var t=this,n=0,i=this.images.length;if(this.hasAnyBroken=!1,!i)return this.complete(),void 0;for(var r=0;i>r;r++){var o=this.images[r];o.on("confirm",e),o.check()}},r.prototype.progress=function(e){this.hasAnyBroken=this.hasAnyBroken||!e.isLoaded;var t=this;setTimeout(function(){t.emit("progress",t,e),t.jqDeferred&&t.jqDeferred.notify(t,e)})},r.prototype.complete=function(){var e=this.hasAnyBroken?"fail":"done";this.isComplete=!0;var t=this;setTimeout(function(){if(t.emit(e,t),t.emit("always",t),t.jqDeferred){var n=t.hasAnyBroken?"reject":"resolve";t.jqDeferred[n](t)}})},o&&(o.fn.imagesLoaded=function(e,t){var n=new r(this,e,t);return n.jqDeferred.promise(o(this))});var f={};return c.prototype=new e,c.prototype.check=function(){var e=f[this.img.src];if(e)return this.useCached(e),void 0;if(f[this.img.src]=this,this.img.complete&&void 0!==this.img.naturalWidth)return this.confirm(0!==this.img.naturalWidth,"naturalWidth"),void 0;var t=this.proxyImage=new Image;n.bind(t,"load",this),n.bind(t,"error",this),t.src=this.img.src},c.prototype.useCached=function(e){if(e.isConfirmed)this.confirm(e.isLoaded,"cached was confirmed");else{var t=this;e.on("confirm",function(e){return t.confirm(e.isLoaded,"cache emitted confirmed"),!0})}},c.prototype.confirm=function(e,t){this.isConfirmed=!0,this.isLoaded=e,this.emit("confirm",this,t)},c.prototype.handleEvent=function(e){var 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var $container = $('.main');
imagesLoaded( $container, function() {
	// stuff goes here
});