Tutorial Multiline String Variables in JavaScript

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This works:

var htmlString = "<div>This is a string.</div>";

This fails:

var htmlSTring = "<div>
  This is a string.
</div>";

Sometimes this is desirable for readability.

Add backslashes to get it to work:

var htmlSTring = "<div>\
  This is a string.\
</div>";

Tutorial Move Cursor to End of Input

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Where el is a reference to an input or textarea.

function moveCursorToEnd(el) {
    if (typeof el.selectionStart == "number") {
        el.selectionStart = el.selectionEnd = el.value.length;
    } else if (typeof el.createTextRange != "undefined") {
        el.focus();
        var range = el.createTextRange();
        range.collapse(false);
        range.select();
    }
}

Reference URL

Javascript Modern Event Handling

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<script type="text/javascript">
/**
 * Attach an event handler on a given Node taking care of Browsers Differences
 * @param {Object} node
 * @param {String} type
 * @param {Function} fn
 * @param {Boolean} capture
 */
function addEventHandler(node,type,fn , capture){
       if(typeof window.event !== "undefined"){
                /* Internet Explorer way */
               node.attachEvent( "on" + type, fn );
       } else {
               /* FF & Other Browsers */
               node.addEventListener( type, fn , capture );
       }
}


/* Example */
addEventHandler(window,"load",function(){
   alert("The page was loaded");
},true)
</script>
This is better than doing the traditional "window.onload" event, as it can attach multiple event handlers to a single event and they all get called.

How to Make HTML5 Elements Work in Old IE

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(function(){if(!/*@cc_on!@*/0)return;var e = "abbr,article,aside,audio,bb,canvas,datagrid,datalist,details,dialog,eventsource,figure,footer,header,hgroup,mark,menu,meter,nav,output,progress,section,time,video".split(','),i=e.length;while(i--){document.createElement(e[i])}})()
Hotlink Script:
<!--[if IE]>
<script src="http://html5shiv.googlecode.com/svn/trunk/html5.js"></script>
<![endif]-->

Tutorial Loop Through Array Without Wasteful Lookups

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Find the length of the array before using it in the for function, so it doesn't need to count the length of the array each iteration (assuming the length won't be changing mid-loop).

var arLen=myArray.length;

for ( var i=0, len=arLen; i<len; i++ ){
  // do something with myArray[i]
}

Tutorial Lighten / Darken Color

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The CSS preprocessors Sass and LESS can take any color and darken() or lighten() it by a specific value. But no such ability is built into JavaScript. This function takes colors in hex format (i.e. #F06D06, with or without hash) and lightens or darkens them with a value.

function LightenDarkenColor(col, amt) {
  
    var usePound = false;
  
    if (col[0] == "#") {
        col = col.slice(1);
        usePound = true;
    }
 
    var num = parseInt(col,16);
 
    var r = (num >> 16) + amt;
 
    if (r > 255) r = 255;
    else if  (r < 0) r = 0;
 
    var b = ((num >> 8) & 0x00FF) + amt;
 
    if (b > 255) b = 255;
    else if  (b < 0) b = 0;
 
    var g = (num & 0x0000FF) + amt;
 
    if (g > 255) g = 255;
    else if (g < 0) g = 0;
 
    return (usePound?"#":"") + (g | (b << 8) | (r << 16)).toString(16);
  
}

Usage

// Lighten
var NewColor = LightenDarkenColor("#F06D06", 20); 

// Darken
var NewColor = LightenDarkenColor("#F06D06", -20);

Demo

Reference URL

Tutorial Lazy Loading Images

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Use a blank.gif as the src of images, and include the width and height of the final image. 

<img src="blank.gif" class="lazy" data-src="http://cdn.css-tricks.com/images/full-size.jpg" width="240" height="152">
/* lazyload.js (c) Lorenzo Giuliani
 * MIT License (http://www.opensource.org/licenses/mit-license.html)
 *
 * expects a list of:  
 * `<img src="blank.gif" data-src="my_image.png" width="600" height="400" class="lazy">`
 */

!function(window){
  var $q = function(q, res){
        if (document.querySelectorAll) {
          res = document.querySelectorAll(q);
        } else {
          var d=document
            , a=d.styleSheets[0] || d.createStyleSheet();
          a.addRule(q,'f:b');
          for(var l=d.all,b=0,c=[],f=l.length;b<f;b++)
            l[b].currentStyle.f && c.push(l[b]);

          a.removeRule(0);
          res = c;
        }
        return res;
      }
    , addEventListener = function(evt, fn){
        window.addEventListener
          ? this.addEventListener(evt, fn, false)
          : (window.attachEvent)
            ? this.attachEvent('on' + evt, fn)
            : this['on' + evt] = fn;
      }
    , _has = function(obj, key) {
        return Object.prototype.hasOwnProperty.call(obj, key);
      }
    ;

  function loadImage (el, fn) {
    var img = new Image()
      , src = el.getAttribute('data-src');
    img.onload = function() {
      if (!! el.parent)
        el.parent.replaceChild(img, el)
      else
        el.src = src;

      fn? fn() : null;
    }
    img.src = src;
  }

  function elementInViewport(el) {
    var rect = el.getBoundingClientRect()

    return (
       rect.top    >= 0
    && rect.left   >= 0
    && rect.top <= (window.innerHeight || document.documentElement.clientHeight)
    )
  }

    var images = new Array()
      , query = $q('img.lazy')
      , processScroll = function(){
          for (var i = 0; i < images.length; i++) {
            if (elementInViewport(images[i])) {
              loadImage(images[i], function () {
                images.splice(i, i);
              });
            }
          };
        }
      ;
    // Array.prototype.slice.call is not callable under our lovely IE8 
    for (var i = 0; i < query.length; i++) {
      images.push(query[i]);
    };

    processScroll();
    addEventListener('scroll',processScroll);

}(this);​

Reference URL