248 lines
7.8 KiB
JavaScript
248 lines
7.8 KiB
JavaScript
/**
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* @Project: ReferrerKiller.
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* @Licence: The MIT License.
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* @Author: Juan Pablo Guereca.
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* @Description: Crossbrowser referrer killing solution.
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* It's a hack that prevents the browser of sending the http referrer in the following cases:
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* - Link: You can have a link in your website being sure that the destiny won't know about your site.
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* - Image: You can display an image from another site being sure the other site won't know your website is displaying it.
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* Other interesting use is displaying an image without blocking the rest of the content, this way in case the image fails
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* it allows the rest of the page to load normally.
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* Uses:
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* - Load static content in parallel.
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* - Provide privacy to your web users.
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* - Saving bandwidth, considering you safe the extra bytes of the http referrer.
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* Abuses:
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* - Stilling bandwidth, using some other site contents (hotlinking, http://en.wikipedia.org/wiki/Inline_linking).
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* @Compatibility:
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* It's been tested successfully on:
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* - Chrome 24.
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* - Firefox 15.
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* - Safari 6.
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* - Opera 12: it sends the referrer in the case of anchors if the target is an iframe, not if it opens in other window
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* or the same one, for images it never sends the referrer even without using the hack.
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* - IE 6, 7, 8.
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* - IE 9: it works for images but not links, that's why in that oogle's url redirection is used for this browser, in this case
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* there is an intermediate page.
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* @Interface:
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* - ReferrerKiller.linkHtml(url, [innerHtml], [anchorParams], [iframeAttributes]). Returns a string.
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* - ReferrerKiller.linkNode(url, [innerHtml], [anchorParams], [iframeAttributes]). Returns an Html Node.
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* - ReferrerKiller.imageHtml(url, [imgParams], [iframeAttributes]). Returns a string.
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* - ReferrerKiller.imageNode(url, [imgParams], [iframeAttributes]). Returns an Html Node.
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*/
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/**
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* @module ReferrerKiller
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*/
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var ReferrerKiller = (function () {
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var URL_REDIRECTION = "https://www.google.com/url?q=", // You can use another service if you use https protocol no referrer will be sent.
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PUB = {},
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IE_GT_8 = (function () {
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/*- Detecting if it's IE greater than 8 -*/
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var trident,
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match = navigator.userAgent.match(/Trident\/(\d)+/);
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if (null === match) {
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return false;
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}
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trident = parseInt(match[1], 10);
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if (isNaN(trident)) {
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return false;
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}
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return trident > 4;
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})();
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/**
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* Escapes double quotes in a string.
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*
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* @private
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* @param {string} str
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* @return {string}
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*/
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function escapeDoubleQuotes(str) {
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return str.split('"').join('\\"');
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}
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/**
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* Given a html string returns an html node.
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*
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* @private
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* @param {string} html
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* @return {Node}
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*/
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function htmlToNode(html) {
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var container = document.createElement('div');
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container.innerHTML = html;
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return container.firstChild;
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}
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/**
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* Converts object to html attributes string.
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*
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* @private
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* @param {object} obj
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* @return {string}
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*/
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function objectToHtmlAttributes(obj) {
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var attributes = [],
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value;
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for (var name in obj) {
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value = obj[name];
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attributes.push(name + '="' + escapeDoubleQuotes(value) + '"');
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}
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return attributes.join(' ');
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}
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/**
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* It applies the hack to kill the referrer to some html.
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*
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* @public
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* @param {string} html.
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* @param {object} [iframeAttributes]
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* @return {string} html.
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*/
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function htmlString(html, iframeAttributes) {
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var iframeAttributes = iframeAttributes || {},
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defaultStyles = 'border:none; overflow:hidden; ',
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id;
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/*-- Setting default styles and letting the option to add more or overwrite them --*/
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if ('style' in iframeAttributes) {
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iframeAttributes.style = defaultStyles + iframeAttributes.style;
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} else {
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iframeAttributes.style = defaultStyles;
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}
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id = '__referrer_killer_' + (new Date).getTime() + Math.floor(Math.random()*9999);
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/*-- Returning html with the hack wrapper --*/
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return '<iframe \
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style="border 1px solid #ff0000" \
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scrolling="no" \
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frameborder="no" \
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allowtransparency="true" ' +
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/*-- Adding style attribute --*/
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objectToHtmlAttributes( iframeAttributes ) +
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'id="' + id + '" ' +
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' src="javascript:\'\
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<!doctype html>\
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<html>\
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<head>\
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<meta charset=\\\'utf-8\\\'>\
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<style>*{margin:0;padding:0;border:0;}</style>\
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</head>' +
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/*-- Function to adapt iframe's size to content's size --*/
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'<script>\
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function resizeWindow() {\
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var elems = document.getElementsByTagName(\\\'*\\\'),\
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width = 0,\
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height = 0,\
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first = document.body.firstChild,\
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elem;\
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if (first.offsetHeight && first.offsetWidth) {\
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width = first.offsetWidth;\
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height = first.offsetHeight;\
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} else {\
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for (var i in elems) {\
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elem = elems[i];\
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if (!elem.offsetWidth) {\
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continue;\
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}\
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width = Math.max(elem.offsetWidth, width);\
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height = Math.max(elem.offsetHeight, height);\
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}\
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}\
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var ifr = parent.document.getElementById(\\\'' + id + '\\\');\
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ifr.height = height;\
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ifr.width = width;\
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}\
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</script>' +
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'<body onload=\\\'resizeWindow()\\\'>\' + decodeURIComponent(\'' +
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/*-- Content --*/
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encodeURIComponent(html) +
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'\') +\'</body></html>\'"></iframe>';
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}
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/*-- Public interface --*/
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/**
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* It creates a link without referrer.
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*
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* @public
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* @param {string} url
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* @param {string} innerHTML
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* @param {object} [anchorParams]
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* @param {object} [iframeAttributes]
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* @return {string} html
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*/
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function linkHtml(url, innerHTML, anchorParams, iframeAttributes) {
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var html,
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urlRedirection = '';
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innerHTML = innerHTML || false;
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/*-- If there is no innerHTML use the url as innerHTML --*/
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if (!innerHTML) {
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innerHTML = url;
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}
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anchorParams = anchorParams || {};
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/*-- Making sure there is a target attribute and the value isn't '_self' --*/
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if (!('target' in anchorParams) || '_self' === anchorParams.target) {
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/*-- Converting _self to _top else it would open in the iframe container --*/
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anchorParams.target = '_top';
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}
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if (IE_GT_8) {
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urlRedirection = URL_REDIRECTION;
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}
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html = '<a rel="noreferrer" href="' + urlRedirection + escapeDoubleQuotes(url) + '" ' + objectToHtmlAttributes(anchorParams) + '>' + innerHTML + '</a>';
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return htmlString(html, iframeAttributes);
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}
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PUB.linkHtml = linkHtml;
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/**
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* It creates a link without referrer.
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*
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* @public
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* @param {String} url
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* @param {String} innerHTML
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* @param {Object} [anchorParams]
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* @param {object} [iframeAttributes]
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* @return {Node}
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*/
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function linkNode(url, innerHTML, anchorParams, iframeAttributes) {
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return htmlToNode(linkHtml(url, innerHTML, anchorParams, iframeAttributes));
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}
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PUB.linkNode = linkNode;
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/**
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* It displays an image without sending the referrer.
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*
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* @public
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* @param {String} url
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* @param {Object} [imgAttributesParam]
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* @return {String} html
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*/
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function imageHtml(url, imgAttributesParam) {
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var imgAttributes = imgAttributesParam || {},
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/*-- Making sure this styles are applyed in the image but let the possibility to overwrite them --*/
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defaultStyles = 'border:none; margin: 0; padding: 0';
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if ('style' in imgAttributes) {
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imgAttributes.style = defaultStyles + imgAttributes.style;
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} else {
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imgAttributes.style = defaultStyles;
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}
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return htmlString('<a rel="noreferrer" href="' + escapeDoubleQuotes(url) + '" target="_BLANK"><img src="' + escapeDoubleQuotes(url) + '" ' + objectToHtmlAttributes(imgAttributes) + '/></a>');
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}
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PUB.imageHtml = imageHtml;
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/**
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* It displays an image without sending the referrer.
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*
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* @public
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* @param {string} url
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* @param {object} [imgParams]
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* @return {Node}
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*/
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function imageNode(url, imgParams) {
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return htmlToNode(imageHtml(url, imgParams));
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}
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PUB.imageNode = imageNode;
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/*-- Exposing the module interface --*/
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return PUB;
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})();
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