1. Include Google Host Library directly:

   <script src="https://ajax.googleapis.com/ajax/libs/webfont/1.6.26/webfont.js"></script>
   <script>
     WebFont.load({
       google: {
         families: ['Droid Sans', 'Droid Serif']
       }
     });
   </script>

2. Include Google Host Library asynchronously:

   <script type="text/javascript">
     WebFontConfig={
       google:{families:["Lato:400,700,300,100:latin"]}
     };
     
     (function(){
       var wf = document.createElement("script");
       wf.src = ("https:" == document.location.protocol ? "https":"http") + 
                "://ajax.googleapis.com/ajax/libs/webfont/1/webfont.js";
       wf.type="text/javascript";
       wf.async="true";
       var t = document.getElementsByTagName("script")[0];
       t.parentNode.insertBefore(wf, t)
     })();
   </script>

You can also download Google WebFont Loader locally and call WebFont.load()  function
For more details, check: https://github.com/typekit/webfontloader

var xDown = null;
var yDown = null;
document.addEventListener('touchstart', handleTouchStart, false);
document.addEventListener('touchmove', handleTouchMove, false);

function handleTouchStart(evt) {
    xDown = evt.touches[0].clientX;
    yDown = evt.touches[0].clientY;
};

function handleTouchMove(evt) {
    if (!xDown || !yDown) {
        return;
    }

    var xUp = evt.touches[0].clientX;
    var yUp = evt.touches[0].clientY;

    var xDiff = xDown - xUp;
    var yDiff = yDown - yUp;

    if (Math.abs(xDiff) > Math.abs(yDiff)) {
        if (xDiff > 0) {
        // swipe right direction
        }
        else {
        // swipe left direction
        }
    }
    else {
        if (yDiff > 0) {
        // swipe down direction
        }
        else {
        // swipe up direction
        }
    }

    /* reset values */
    xDown = null;
    yDown = null;
};

Unbind event:

$('body').unbind('touchmove');

2. Direction Arrow Keys Binding

// set key binding for direction arrows
$(document).keydown(function(e) {
    switch(e.which) {
        case 37:
        // left direction
        break;

        case 38:
        // up direction
        break;

        case 39:
        // right direction
        break;

        case 40:
        // down direction
        break;

        default: return; // exit this handler for other keys
    }
    e.preventDefault(); // prevent the default action (scroll / move caret)
});

Unbind event:

$(document).unbind('keydown');

3. Mouse move direction events

var last_position = {};

$(document).on('mousemove', function (event) {
    //check to make sure there is data to compare against
    if (typeof(last_position.x) != 'undefined') {

        //get the change from last position to this position
        var deltaX = last_position.x - event.clientX,
        deltaY = last_position.y - event.clientY;

        //check which direction had the highest amplitude and then figure out direction by checking if the value is greater or less than zero
        if (Math.abs(deltaX) > Math.abs(deltaY) && deltaX > 0) {
            // mouse move left
        }
        else if (Math.abs(deltaX) > Math.abs(deltaY) && deltaX < 0) {
            // mouse move right
        }
        else if (Math.abs(deltaY) > Math.abs(deltaX) && deltaY > 0) {
            // mouse move up
        }
        else if (Math.abs(deltaY) > Math.abs(deltaX) && deltaY < 0) {
            // mouse move down
        }
    }

    //set the new last position to the current for next time
    last_position = {
        x : event.clientX,
        y : event.clientY
    };
});

Unbind event:

$(document).off('mousemove');

1. String

   • Proper Case (Convert string to Proper/Title Case)

     // convert string to proper case
     String.prototype.toProperCase = function () {
         return this.replace(/\w\S*/g, function(txt){return txt.charAt(0).toUpperCase() + txt.substr(1).toLowerCase();});
     };
     

     Usage:

     'your name'.toProperCase();
     Output: 'Your Name'

   • Snake Case (Convert studly case ‘YourName’ to ‘your_name’)

     // convert string to snake case
     String.prototype.toSnakeCase = function () {
         return this.replace(/(.)([A-Z])/g, "$1_$2").toLowerCase();
     };

     Usage:

     'YourName'.toSnakeCase();
     Output: 'your_name'

   • Is Date (Check if string is a Date)

     // check if string is a valid date
     String.prototype.isDate = function () {
         var dateFormat;
     
         if (toString.call(this) === '[object Date]') {
             return true;
         }
         if (typeof this.replace === 'function') {
             this.replace(/^\s+|\s+$/gm, '');
         }
     
         dateFormat = /(^\d{1,4}[\.|\\/|-]\d{1,2}[\.|\\/|-]\d{1,4})(\s*(?:0?[1-9]:[0-5]|1(?=[012])\d:[0-5])\d\s*[ap]m)?$/;
     
         if (dateFormat.test(this)) {
             return !!new Date(this).getTime();
         }
     
         return false;
     };

     Usage:

     '12-03-1990'.isDate();
     Output: true

   • Is Time (Check if string is a Time)

     // check if string is a time
     String.prototype.isTime = function () {
         var isValid = /^([0-1]?[0-9]|2[0-3]):([0-5][0-9])(:[0-5][0-9])?$/.test(this);
         return isValid;
     };

     Usage:

     '14:36'.isTime();
     Output: true

   • Is DateTime (Check if string is DateTime, to make it working, copy the above Date & Time Prototype)

     // check if string is a time
     String.prototype.isDateTime = function () {
         var date = this.split(" ");
     
         if (date[0].isDate() && date[1].isTime()) {
             return true;
         }
     
         return false;
     };

     Usage:

     '20-10-1990 14:36'.isDateTime();
     Output: true

2. Date (Get Long and Short Month Names with Multilingual Support)

   • Month Long Name

     // getting month long name from Date object
     Date.prototype.getMonthName = function(lang) {
         lang = lang && (lang in Date.locale) ? lang : 'en';
         return Date.locale[lang].month_names[this.getMonth()];
     };

   • Month Short Name

     // getting month short name from Date object
     Date.prototype.getMonthNameShort = function(lang) {
         lang = lang && (lang in Date.locale) ? lang : 'en';
         return Date.locale[lang].month_names_short[this.getMonth()];
     };

   • Date Locale(Multilingual Support)

     Date.locale = {
         en: {
             month_names: ['January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December'],
             month_names_short: ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec']
         }
     };

     Usage:

     var current_month = new Date().getMonthName(lang);
     var current_short_name = new Date().getMonthNameShort(lang);

     lang parameter is optional

3. Array

   • Contains (Check if given element exists in Array, similar to jQuery inArray)

     Array.prototype.contains = function(obj) {
         var i = this.length;
         while (i--) {
             if (this[i] === obj) {
                 return true;
             }
         }
         return false;
     }

     Usage:

     ['Red', 'Yellow', 'Green', 'Blue'].contains('Green');
     Output: true

   • Random (Pick a random element from array)

     Array.prototype.random = function () {
         return this[Math.floor((Math.random()*this.length))];
     }

     Usage:

     [1, 2, 3, 4].random();

4.  Storage

   • Set Object in LocalStorage/SessionStorage

     Storage.prototype.setObject = function(key, value) {
         this.setItem(key, JSON.stringify(value));
     }

     Usage:

     localStorage.setObject('numbers', [1, 2, 3, 4]);

   • Get Object from LocalStorage/Session

     Storage.prototype.getObject = function(key) {
         var value = this.getItem(key);
         return value && JSON.parse(value);
     }

     Usage:

     localStorage.getObject('numbers');

Javascript code to open window popup center aligned to page with close event on button click:

$(btn-container).on("click", function() {
    var w = 620;
    var h = 350;
    var win = window.open('http://achieveee.com', 'Achieveee', 'resizable,toolbar=0,location=0,scrollbars=1,menubar=0,width='+w+',height='+h+',top='+(screen.height-h)/2+',left='+(screen.width-w)/2+'');

    var timer = setInterval(function() {
        if (win.closed) {
            clearInterval(timer);
            alert('closed');
        }
    }, 1000);
});