Some utility script that I have used (at times) and might want to use later in my projects.

utils.js

/**
 * Checks if an object is empty or not.
 */
Object.prototype.isEmpty = function() {
    for(var key in this) {
        if (this.hasOwnProperty(key)) {
            return false;
        }
    }
    return true;
}

/**
 * Converts native strings to strings in title case.
 */
String.prototype.toTitleCase = function() {
    return this.replace(/\w\S*/g, function(txt){return txt.charAt(0).toUpperCase() + txt.substr(1).toLowerCase();});
}

/**
 * Checks if an element is completely visible in browser's viewport or not.
 */
function elementInViewport(el) {
     var rect = el.getBoundingClientRect()

     return (
         rect.top >= 0 &&
         rect.left >= 0 &&
         rect.bottom <= window.innerHeight &&
         rect.right <= window.innerWidth 
     )
}

/**
 * Checks if any part of an element is visible in browser's viewport.
 */
function inViewport (el) {
    var r, html;
    if ( !el || 1 !== el.nodeType ) { return false; }
    html = document.documentElement;
    r = el.getBoundingClientRect();

    return ( !!r 
      && r.bottom >= 0 
      && r.right >= 0 
      && r.top <= html.clientHeight 
      && r.left <= html.clientWidth 
    );
}