by Unknown in javascript , Tutorial 0
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]
}
by Unknown in javascript , Tutorial 0
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);
}// Lighten
var NewColor = LightenDarkenColor("#F06D06", 20);
// Darken
var NewColor = LightenDarkenColor("#F06D06", -20); by Unknown in javascript , Tutorial 0
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);by Unknown in javascript , Tutorial 0
As in, what keyboard events report based on what keys are pressed.
$("#textinput").keydown(function(e) {
e.keyCode; // this value
});
|
|
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by Unknown in javascript , Tutorial 0
JavaScript-required area is hidden with inline CSS, and then shown after it loads with a small snippet of JavaScript. Below that, noscript tags are used for fallback content. So only one or the other of these bits of content will be required depending on if JavaScript is enabled or not.
<!-- JavaScript-Required Content -->
<div id="photoslider" style="display:none">Javascript photoslider</div>
<script>document.getElementById('photoslider').style.display='';</script>
<!-- END JavaScript-Required Content -->
<!-- Fallback Content -->
<noscript><div id="photo">Alternative static photo as content when javascript is turned off</div></noscript>
<!-- END Fallback Content -->by Unknown in javascript , Tutorial 0
var MD5 = function (string) {
function RotateLeft(lValue, iShiftBits) {
return (lValue<<iShiftBits) | (lValue>>>(32-iShiftBits));
}
function AddUnsigned(lX,lY) {
var lX4,lY4,lX8,lY8,lResult;
lX8 = (lX & 0x80000000);
lY8 = (lY & 0x80000000);
lX4 = (lX & 0x40000000);
lY4 = (lY & 0x40000000);
lResult = (lX & 0x3FFFFFFF)+(lY & 0x3FFFFFFF);
if (lX4 & lY4) {
return (lResult ^ 0x80000000 ^ lX8 ^ lY8);
}
if (lX4 | lY4) {
if (lResult & 0x40000000) {
return (lResult ^ 0xC0000000 ^ lX8 ^ lY8);
} else {
return (lResult ^ 0x40000000 ^ lX8 ^ lY8);
}
} else {
return (lResult ^ lX8 ^ lY8);
}
}
function F(x,y,z) { return (x & y) | ((~x) & z); }
function G(x,y,z) { return (x & z) | (y & (~z)); }
function H(x,y,z) { return (x ^ y ^ z); }
function I(x,y,z) { return (y ^ (x | (~z))); }
function FF(a,b,c,d,x,s,ac) {
a = AddUnsigned(a, AddUnsigned(AddUnsigned(F(b, c, d), x), ac));
return AddUnsigned(RotateLeft(a, s), b);
};
function GG(a,b,c,d,x,s,ac) {
a = AddUnsigned(a, AddUnsigned(AddUnsigned(G(b, c, d), x), ac));
return AddUnsigned(RotateLeft(a, s), b);
};
function HH(a,b,c,d,x,s,ac) {
a = AddUnsigned(a, AddUnsigned(AddUnsigned(H(b, c, d), x), ac));
return AddUnsigned(RotateLeft(a, s), b);
};
function II(a,b,c,d,x,s,ac) {
a = AddUnsigned(a, AddUnsigned(AddUnsigned(I(b, c, d), x), ac));
return AddUnsigned(RotateLeft(a, s), b);
};
function ConvertToWordArray(string) {
var lWordCount;
var lMessageLength = string.length;
var lNumberOfWords_temp1=lMessageLength + 8;
var lNumberOfWords_temp2=(lNumberOfWords_temp1-(lNumberOfWords_temp1 % 64))/64;
var lNumberOfWords = (lNumberOfWords_temp2+1)*16;
var lWordArray=Array(lNumberOfWords-1);
var lBytePosition = 0;
var lByteCount = 0;
while ( lByteCount < lMessageLength ) {
lWordCount = (lByteCount-(lByteCount % 4))/4;
lBytePosition = (lByteCount % 4)*8;
lWordArray[lWordCount] = (lWordArray[lWordCount] | (string.charCodeAt(lByteCount)<<lBytePosition));
lByteCount++;
}
lWordCount = (lByteCount-(lByteCount % 4))/4;
lBytePosition = (lByteCount % 4)*8;
lWordArray[lWordCount] = lWordArray[lWordCount] | (0x80<<lBytePosition);
lWordArray[lNumberOfWords-2] = lMessageLength<<3;
lWordArray[lNumberOfWords-1] = lMessageLength>>>29;
return lWordArray;
};
function WordToHex(lValue) {
var WordToHexValue="",WordToHexValue_temp="",lByte,lCount;
for (lCount = 0;lCount<=3;lCount++) {
lByte = (lValue>>>(lCount*8)) & 255;
WordToHexValue_temp = "0" + lByte.toString(16);
WordToHexValue = WordToHexValue + WordToHexValue_temp.substr(WordToHexValue_temp.length-2,2);
}
return WordToHexValue;
};
function Utf8Encode(string) {
string = string.replace(/\r\n/g,"\n");
var utftext = "";
for (var n = 0; n < string.length; n++) {
var c = string.charCodeAt(n);
if (c < 128) {
utftext += String.fromCharCode(c);
}
else if((c > 127) && (c < 2048)) {
utftext += String.fromCharCode((c >> 6) | 192);
utftext += String.fromCharCode((c & 63) | 128);
}
else {
utftext += String.fromCharCode((c >> 12) | 224);
utftext += String.fromCharCode(((c >> 6) & 63) | 128);
utftext += String.fromCharCode((c & 63) | 128);
}
}
return utftext;
};
var x=Array();
var k,AA,BB,CC,DD,a,b,c,d;
var S11=7, S12=12, S13=17, S14=22;
var S21=5, S22=9 , S23=14, S24=20;
var S31=4, S32=11, S33=16, S34=23;
var S41=6, S42=10, S43=15, S44=21;
string = Utf8Encode(string);
x = ConvertToWordArray(string);
a = 0x67452301; b = 0xEFCDAB89; c = 0x98BADCFE; d = 0x10325476;
for (k=0;k<x.length;k+=16) {
AA=a; BB=b; CC=c; DD=d;
a=FF(a,b,c,d,x[k+0], S11,0xD76AA478);
d=FF(d,a,b,c,x[k+1], S12,0xE8C7B756);
c=FF(c,d,a,b,x[k+2], S13,0x242070DB);
b=FF(b,c,d,a,x[k+3], S14,0xC1BDCEEE);
a=FF(a,b,c,d,x[k+4], S11,0xF57C0FAF);
d=FF(d,a,b,c,x[k+5], S12,0x4787C62A);
c=FF(c,d,a,b,x[k+6], S13,0xA8304613);
b=FF(b,c,d,a,x[k+7], S14,0xFD469501);
a=FF(a,b,c,d,x[k+8], S11,0x698098D8);
d=FF(d,a,b,c,x[k+9], S12,0x8B44F7AF);
c=FF(c,d,a,b,x[k+10],S13,0xFFFF5BB1);
b=FF(b,c,d,a,x[k+11],S14,0x895CD7BE);
a=FF(a,b,c,d,x[k+12],S11,0x6B901122);
d=FF(d,a,b,c,x[k+13],S12,0xFD987193);
c=FF(c,d,a,b,x[k+14],S13,0xA679438E);
b=FF(b,c,d,a,x[k+15],S14,0x49B40821);
a=GG(a,b,c,d,x[k+1], S21,0xF61E2562);
d=GG(d,a,b,c,x[k+6], S22,0xC040B340);
c=GG(c,d,a,b,x[k+11],S23,0x265E5A51);
b=GG(b,c,d,a,x[k+0], S24,0xE9B6C7AA);
a=GG(a,b,c,d,x[k+5], S21,0xD62F105D);
d=GG(d,a,b,c,x[k+10],S22,0x2441453);
c=GG(c,d,a,b,x[k+15],S23,0xD8A1E681);
b=GG(b,c,d,a,x[k+4], S24,0xE7D3FBC8);
a=GG(a,b,c,d,x[k+9], S21,0x21E1CDE6);
d=GG(d,a,b,c,x[k+14],S22,0xC33707D6);
c=GG(c,d,a,b,x[k+3], S23,0xF4D50D87);
b=GG(b,c,d,a,x[k+8], S24,0x455A14ED);
a=GG(a,b,c,d,x[k+13],S21,0xA9E3E905);
d=GG(d,a,b,c,x[k+2], S22,0xFCEFA3F8);
c=GG(c,d,a,b,x[k+7], S23,0x676F02D9);
b=GG(b,c,d,a,x[k+12],S24,0x8D2A4C8A);
a=HH(a,b,c,d,x[k+5], S31,0xFFFA3942);
d=HH(d,a,b,c,x[k+8], S32,0x8771F681);
c=HH(c,d,a,b,x[k+11],S33,0x6D9D6122);
b=HH(b,c,d,a,x[k+14],S34,0xFDE5380C);
a=HH(a,b,c,d,x[k+1], S31,0xA4BEEA44);
d=HH(d,a,b,c,x[k+4], S32,0x4BDECFA9);
c=HH(c,d,a,b,x[k+7], S33,0xF6BB4B60);
b=HH(b,c,d,a,x[k+10],S34,0xBEBFBC70);
a=HH(a,b,c,d,x[k+13],S31,0x289B7EC6);
d=HH(d,a,b,c,x[k+0], S32,0xEAA127FA);
c=HH(c,d,a,b,x[k+3], S33,0xD4EF3085);
b=HH(b,c,d,a,x[k+6], S34,0x4881D05);
a=HH(a,b,c,d,x[k+9], S31,0xD9D4D039);
d=HH(d,a,b,c,x[k+12],S32,0xE6DB99E5);
c=HH(c,d,a,b,x[k+15],S33,0x1FA27CF8);
b=HH(b,c,d,a,x[k+2], S34,0xC4AC5665);
a=II(a,b,c,d,x[k+0], S41,0xF4292244);
d=II(d,a,b,c,x[k+7], S42,0x432AFF97);
c=II(c,d,a,b,x[k+14],S43,0xAB9423A7);
b=II(b,c,d,a,x[k+5], S44,0xFC93A039);
a=II(a,b,c,d,x[k+12],S41,0x655B59C3);
d=II(d,a,b,c,x[k+3], S42,0x8F0CCC92);
c=II(c,d,a,b,x[k+10],S43,0xFFEFF47D);
b=II(b,c,d,a,x[k+1], S44,0x85845DD1);
a=II(a,b,c,d,x[k+8], S41,0x6FA87E4F);
d=II(d,a,b,c,x[k+15],S42,0xFE2CE6E0);
c=II(c,d,a,b,x[k+6], S43,0xA3014314);
b=II(b,c,d,a,x[k+13],S44,0x4E0811A1);
a=II(a,b,c,d,x[k+4], S41,0xF7537E82);
d=II(d,a,b,c,x[k+11],S42,0xBD3AF235);
c=II(c,d,a,b,x[k+2], S43,0x2AD7D2BB);
b=II(b,c,d,a,x[k+9], S44,0xEB86D391);
a=AddUnsigned(a,AA);
b=AddUnsigned(b,BB);
c=AddUnsigned(c,CC);
d=AddUnsigned(d,DD);
}
var temp = WordToHex(a)+WordToHex(b)+WordToHex(c)+WordToHex(d);
return temp.toLowerCase();
}MD5("whatever");Like possibly snagging a Gravatar.
by Unknown in javascript , Tutorial 0
Javascript objects are really nice, but sometimes they are missing some useful little functions/methods. The example above is with Arrays. It's really nice to know whether or not an item is contained within your array. Well you can write a function that takes the array and the item you're checking for, but it's much cleaner to add the contains( item ) method to the Array object.
/**
* Array.prototype.[method name] allows you to define/overwrite an objects method
* needle is the item you are searching for
* this is a special variable that refers to "this" instance of an Array.
* returns true if needle is in the array, and false otherwise
*/
Array.prototype.contains = function ( needle ) {
for (i in this) {
if (this[i] == needle) return true;
}
return false;
}// Now you can do things like:
var x = Array();
if (x.contains('foo')) {
// do something special
}