d07d013b30
- pulled ESM modules for local loading. - added downshow module for better HTML to MD conversion.
231 lines
8.1 KiB
JavaScript
231 lines
8.1 KiB
JavaScript
/**
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* downshow.js -- A javascript library to convert HTML to markdown.
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*
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* Copyright (c) 2013 Alex Cornejo.
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*
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* Original Markdown Copyright (c) 2004-2005 John Gruber
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* <http://darlingfireball.net/projects/markdown/>
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*
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* Redistributable under a BSD-style open source license.
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*
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* downshow has no external dependencies. It has been tested in chrome and
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* firefox, it probably works in internet explorer, but YMMV.
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*
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* Basic Usage:
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*
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* downshow(document.getElementById('#yourid').innerHTML);
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*
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* TODO:
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* - Remove extra whitespace between words in headers and other places.
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*/
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(function () {
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var doc;
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// Use browser DOM with jsdom as a fallback (for node.js)
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try {
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doc = document;
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} catch(e) {
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var jsdom = require("jsdom").jsdom;
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doc = jsdom("<html><head></head><body></body></html>");
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}
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/**
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* Returns every element in root in their bfs traversal order.
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*
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* In the process it transforms any nested lists to conform to the w3c
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* standard, see: http://www.w3.org/wiki/HTML_lists#Nesting_lists
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*/
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function bfsOrder(root) {
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var inqueue = [root], outqueue = [];
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root._bfs_parent = null;
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while (inqueue.length > 0) {
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var elem = inqueue.shift();
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outqueue.push(elem);
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var children = elem.childNodes;
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var liParent = null;
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for (var i=0 ; i<children.length; i++) {
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if (children[i].nodeType == 1) {// element node
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if (children[i].tagName === 'LI') {
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liParent = children[i];
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} else if ((children[i].tagName === 'UL' || children[i].tagName === 'OL') && liParent) {
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liParent.appendChild(children[i]);
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i--;
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continue;
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}
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children[i]._bfs_parent = elem;
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inqueue.push(children[i]);
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}
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}
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}
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outqueue.shift();
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return outqueue;
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}
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/**
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* Remove whitespace and newlines from beginning and end of a sting.
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*/
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function trim(str) {
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return str.replace(/^\s\s*/,'').replace(/\s\s*$/, '');
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}
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/**
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* Remove all newlines and trims the resulting string.
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*/
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function nltrim(str) {
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return str.replace(/\s{2,}/g, ' ').replace(/^\s\s*/,'').replace(/\s\s*$/, '');
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}
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/**
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* Add prefix to the beginning of every line in block.
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*/
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function prefixBlock(prefix, block, skipEmpty) {
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var lines = block.split('\n');
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for (var i =0; i<lines.length; i++) {
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// Do not prefix empty lines
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if (lines[i].length === 0 && skipEmpty === true)
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continue;
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else
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lines[i] = prefix + lines[i];
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}
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return lines.join('\n');
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}
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/**
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* Set the node's content.
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*/
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function setContent(node, content, prefix, suffix) {
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if (content.length > 0) {
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if (prefix && suffix)
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node._bfs_text = prefix + content + suffix;
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else
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node._bfs_text = content;
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} else
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node._bfs_text = '';
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}
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/**
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* Get a node's content.
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*/
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function getContent(node) {
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var text = '', atom;
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for (var i = 0; i<node.childNodes.length; i++) {
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if (node.childNodes[i].nodeType === 1) {
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atom = node.childNodes[i]._bfs_text;
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} else if (node.childNodes[i].nodeType === 3) {
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atom = node.childNodes[i].data;
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} else
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continue;
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if (text.match(/[\t ]+$/) && atom.match(/^[\t ]+/)) {
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text = text.replace(/[\t ]+$/,'') + ' ' + atom.replace(/^[\t ]+/, '');
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} else {
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text = text + atom;
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}
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}
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return text;
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}
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/**
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* Process a node in the DOM tree.
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* */
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function processNode(node) {
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if (node.tagName === 'P' || node.tagName === 'DIV' || node.tagName === 'UL' || node.tagName === 'OL' || node.tagName === 'PRE')
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setContent(node, getContent(node), '\n\n', '\n\n');
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else if (node.tagName === 'BR')
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setContent(node, '\n\n');
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else if (node.tagName === 'HR')
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setContent(node, '\n***\n');
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else if (node.tagName === 'H1')
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setContent(node, nltrim(getContent(node)), '\n# ', '\n');
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else if (node.tagName === 'H2')
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setContent(node, nltrim(getContent(node)), '\n## ', '\n');
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else if (node.tagName === 'H3')
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setContent(node, nltrim(getContent(node)), '\n### ', '\n');
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else if (node.tagName === 'H4')
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setContent(node, nltrim(getContent(node)), '\n#### ', '\n');
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else if (node.tagName === 'H5')
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setContent(node, nltrim(getContent(node)), '\n##### ', '\n');
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else if (node.tagName === 'H6')
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setContent(node, nltrim(getContent(node)), '\n###### ', '\n');
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else if (node.tagName === 'B' || node.tagName === 'STRONG')
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setContent(node, nltrim(getContent(node)), '**', '**');
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else if (node.tagName === 'I' || node.tagName === 'EM')
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setContent(node, nltrim(getContent(node)), '_', '_');
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else if (node.tagName === 'A') {
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var href = node.href ? nltrim(node.href) : '', text = nltrim(getContent(node)) || href, title = node.title ? nltrim(node.title) : '';
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if (href.length > 0)
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setContent(node, '[' + text + '](' + href + (title ? ' "' + title + '"' : '') + ')');
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else
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setContent(node, '');
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} else if (node.tagName === 'IMG') {
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var src = node.getAttribute('src') ? nltrim(node.getAttribute('src')) : '', alt = node.alt ? nltrim(node.alt) : '', caption = node.title ? nltrim(node.title) : '';
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if (src.length > 0)
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setContent(node, '![' + alt + '](' + src + (caption ? ' "' + caption + '"' : '') + ')');
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else
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setContent(node, '');
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} else if (node.tagName === 'BLOCKQUOTE') {
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var block_content = getContent(node);
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if (block_content.length > 0)
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setContent(node, prefixBlock('> ', block_content), '\n\n', '\n\n');
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else
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setContent(node, '');
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} else if (node.tagName === 'CODE') {
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if (node._bfs_parent.tagName === 'PRE' && node._bfs_parent._bfs_parent !== null)
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setContent(node, prefixBlock(' ', getContent(node)));
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else
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setContent(node, nltrim(getContent(node)), '`', '`');
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} else if (node.tagName === 'LI') {
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var list_content = getContent(node);
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if (list_content.length > 0)
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if (node._bfs_parent.tagName === 'OL')
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setContent(node, trim(prefixBlock(' ', list_content, true)), '1. ', '\n\n');
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else
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setContent(node, trim(prefixBlock(' ', list_content, true)), '- ', '\n\n');
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else
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setContent(node, '');
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} else
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setContent(node, getContent(node));
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}
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function downshow(html, options) {
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var root = doc.createElement('pre');
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root.innerHTML = html;
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var nodes = bfsOrder(root).reverse(), i;
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if (options && options.nodeParser) {
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for (i = 0; i<nodes.length; i++) {
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var result = options.nodeParser(doc, nodes[i].cloneNode(true));
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if (result === false)
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processNode(nodes[i]);
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else
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setContent(nodes[i], result);
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}
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} else {
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for (i = 0; i<nodes.length; i++) {
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processNode(nodes[i]);
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}
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}
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return getContent(root)
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// remove empty lines between blockquotes
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.replace(/(\n(?:> )+[^\n]*)\n+(\n(?:> )+)/g, "$1\n$2")
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// remove empty blockquotes
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.replace(/\n((?:> )+[ ]*\n)+/g, '\n\n')
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// remove extra newlines
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.replace(/\n[ \t]*(?:\n[ \t]*)+\n/g,'\n\n')
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// remove trailing whitespace
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.replace(/\s\s*$/, '')
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// convert lists to inline when not using paragraphs
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.replace(/^([ \t]*(?:\d+\.|\+|\-)[^\n]*)\n\n+(?=[ \t]*(?:\d+\.|\+|\-|\*)[^\n]*)/gm, "$1\n")
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// remove starting newlines
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.replace(/^\n\n*/, '');
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}
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// Export for use in server and client.
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if (typeof module !== 'undefined' && typeof module.exports !== 'undefined')
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module.exports = downshow;
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else if (typeof define === 'function' && define.amd)
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define([], function () {return downshow;});
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else
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window.downshow = downshow;
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})(); |