修改了一个HTML2Markdown 函数

最初的版本是从这里找来的：Html转换为MarkDown样式代码
我给它加了一个过滤掉span、font的功能，并能把表格合理地转换成Markdown编码。

javascriptvar toMarkdown=function(string){
    var ELEMENTS=[
        {patterns:'p',replacement:function(str,attrs,innerHTML){return innerHTML?'\n\n'+innerHTML+'\n':'';}},
        {patterns:'br',type:'void',replacement:'\n'},
        {patterns:'h([1-6])',replacement:function(str,hLevel,attrs,innerHTML){var hPrefix='';for(var i=0;i<hLevel;i++){hPrefix+='#';}return'\n\n'+hPrefix+' '+innerHTML+'\n';}},
        {patterns:'hr',type:'void',replacement:'\n\n* * *\n'},
        {patterns:'a',replacement:function(str,attrs,innerHTML){var href=attrs.match(attrRegExp('href')),title=attrs.match(attrRegExp('title'));return href?'['+innerHTML+']'+'('+href[1]+(title&&title[1]?' "'+title[1]+'"':'')+')':str;}},
        {patterns:['b','strong'],replacement:function(str,attrs,innerHTML){return innerHTML?'**'+innerHTML+'**':'';}},
        {patterns:['i','em'],replacement:function(str,attrs,innerHTML){return innerHTML?'_'+innerHTML+'_':'';}},
        {patterns:'code',replacement:function(str,attrs,innerHTML){return innerHTML?'`'+innerHTML.replace(/<.*?>/ig,'')+'`':'';}},
        // 下面这部分是我自己写的。
        {patterns:'table',replacement:function(str,attrs,innerHTML){
            innerHTML=innerHTML.replace(/<\/tr>/ig,'\r\n').replace(/<tr(\s[^>]+)?>/ig,'|').replace(/<\/t[hd]>/ig,'|').replace(/<t[hd](\s[^>]+)?>/ig,'').replace(/<\/?tbody[^>]*?>/ig,'').replace(/<thead(\s[^>]+)?>([\s\S]*?)\n<\/thead>/ig,function(all,a,b){
                return b+b.replace(/[^|]+/g,'--').replace('|--|','|')+'|\n';
                });
            return '\n'+innerHTML+'\n';
            }},
        {patterns:['font','span'],replacement:function(str,attrs,innerHTML){return innerHTML;}},
        // 上面的内容是我自己写的
        {patterns:'pre',replacement:function(str,attrs,innerHTML){return innerHTML?'```\n'+innerHTML+'\n```\n':''}},
        {patterns:'img',type:'void',replacement:function(str,attrs,innerHTML){
            var src=attrs.match(attrRegExp('src')),alt=attrs.match(attrRegExp('alt')),title=attrs.match(attrRegExp('title'));
            return'!['+(alt&&alt[1]?alt[1]:'')+']'+'('+src[1]+(title&&title[1]?' "'+title[1]+'"':'')+')';}
        }
    ];
    for(var i=0,len=ELEMENTS.length;i<len;i++){
        if(typeof ELEMENTS[i].patterns==='string'){
            string=replaceEls(string,{tag:ELEMENTS[i].patterns,replacement:ELEMENTS[i].replacement,type:ELEMENTS[i].type});
            }
        else{
            for(var j=0,pLen=ELEMENTS[i].patterns.length;j<pLen;j++){
                string=replaceEls(string,{tag:ELEMENTS[i].patterns[j],replacement:ELEMENTS[i].replacement,type:ELEMENTS[i].type});
                }
            }
        }
    function replaceEls(html,elProperties){
        var pattern=elProperties.type==='void'?'<'+elProperties.tag+'\\b([^>]*)\\/?>':'<'+elProperties.tag+'\\b([^>]*)>([\\s\\S]*?)<\\/'+elProperties.tag+'>',regex=new RegExp(pattern,'gi'),markdown='';
        if(typeof elProperties.replacement==='string'){
            markdown=html.replace(regex,elProperties.replacement);
            }
        else{
            markdown=html.replace(regex,function(str,p1,p2,p3){
                return elProperties.replacement.call(this,str,p1,p2,p3);
                });
            }
        return markdown;
        }
    function attrRegExp(attr){
        return new RegExp(attr+'\\s*=\\s*["\']?([^"\']*)["\']?','i');
        }
    string=string.replace(/<pre\b[^>]*>`([\s\S]*)`<\/pre>/gi,function(str,innerHTML){
        innerHTML=innerHTML.replace(/^\t+/g,'  ');
        innerHTML=innerHTML.replace(/\n/g,'\n    ');
        return'\n\n    '+innerHTML+'\n';
        });
    string=string.replace(/^(\s{0,3}\d+)\. /g,'$1\\. ');
    var noChildrenRegex=/<(ul|ol)\b[^>]*>(?:(?!<ul|<ol)[\s\S])*?<\/\1>/gi;
    while(string.match(noChildrenRegex)){
        string=string.replace(noChildrenRegex,function(str){return replaceLists(str);});
        }
    function replaceLists(html){
        html=html.replace(/<(ul|ol)\b[^>]*>([\s\S]*?)<\/\1>/gi,function(str,listType,innerHTML){
            var lis=innerHTML.split('</li>');
            lis.splice(lis.length-1,1);
            for(i=0,len=lis.length;i<len;i++){
                if(lis[i]){
                    var prefix=(listType==='ol')?(i+1)+".  ":"*   ";
                    lis[i]=lis[i].replace(/\s*<li[^>]*>([\s\S]*)/i,function(str,innerHTML){
                        innerHTML=innerHTML.replace(/^\s+/,'');
                        innerHTML=innerHTML.replace(/\n\n/g,'\n\n    ');
                        innerHTML=innerHTML.replace(/\n([ ]*)+(\*|\d+\.) /g,'\n$1    $2 ');
                        return prefix+innerHTML;
                        });
                    }
                }
            return lis.join('\n');
            });
        return'\n\n'+html.replace(/[ \t]+\n|\s+$/g,'');
        }
    var deepest=/<blockquote\b[^>]*>((?:(?!<blockquote)[\s\S])*?)<\/blockquote>/gi;
    while(string.match(deepest)){
        string=string.replace(deepest,function(str){return replaceBlockquotes(str);});
        }
    function replaceBlockquotes(html){
        html=html.replace(/<blockquote\b[^>]*>([\s\S]*?)<\/blockquote>/gi,function(str,inner){
            inner=inner.replace(/^\s+|\s+$/g,'');
            inner=cleanUp(inner);
            inner=inner.replace(/^/gm,'> ');
            inner=inner.replace(/^(>([ \t]{2,}>)+)/gm,'> >');
            return inner;
            });
        return html;
        }
    function cleanUp(string){
        string=string.replace(/^[\t\r\n]+|[\t\r\n]+$/g,'');
        string=string.replace(/\n\s+\n/g,'\n\n');
        string=string.replace(/\n{3,}/g,'\n\n');
        return string;
        }
    return cleanUp(string);
    };
if(typeof exports==='object'){exports.toMarkdown=toMarkdown;}

稍微又做了点修改，让没有表头的表格也能正常地转换成MarkDown。

javascriptvar toMarkdown=function(string){
    var ELEMENTS=[
        {patterns:'p',replacement:function(str,attrs,innerHTML){return innerHTML?'\n\n'+innerHTML+'\n':'';}},
        {patterns:'br',isvoid:true,replacement:'\n'},
        {patterns:'h([1-6])',replacement:function(str,hLevel,attrs,innerHTML){var hPrefix='';for(var i=0;i<hLevel;i++){hPrefix+='#';}return'\n\n'+hPrefix+' '+innerHTML+'\n';}},
        {patterns:'hr',isvoid:true,replacement:'\n\n* * *\n'},
        {patterns:'a',replacement:function(str,attrs,innerHTML){var href=attrs.match(attrRegExp('href')),title=attrs.match(attrRegExp('title'));return href?'['+innerHTML+']'+'('+href[1]+(title&&title[1]?' "'+title[1]+'"':'')+')':str;}},
        {patterns:['b','strong'],replacement:function(str,attrs,innerHTML){return innerHTML?'**'+innerHTML+'**':'';}},
        {patterns:['i','em'],replacement:function(str,attrs,innerHTML){return innerHTML?'_'+innerHTML+'_':'';}},
        {patterns:'code',replacement:function(str,attrs,innerHTML){return innerHTML?'`'+innerHTML.replace(/<.*?>/ig,'')+'`':'';}},
        {patterns:'table',replacement:function(str,attrs,innerHTML){
            innerHTML=innerHTML.replace(/\r?\n/g,'').replace(/<\/tr>/ig,'\n').replace(/<tr(\s[^>]+)?>/ig,'|').replace(/<\/t[hd]>/ig,'|').replace(/<t[hd](\s[^>]+)?>/ig,'').replace(/<\/?tbody[^>]*?>/ig,'').replace(/<\/?thead[^>]*?>/ig,'').replace(/^(.*?)\n/,function(all,b){
                return b+'\n'+b.replace(/[^|]+/g,'--')+'\n';
                });
            return '\n'+innerHTML+'\n';
            }},
        //{patterns:['font','span','div','section','article','aside','div','div','div','span'],replacement:function(str,attrs,innerHTML){return innerHTML;}},
        {patterns:'pre',replacement:function(str,attrs,innerHTML){return innerHTML?'```\n'+innerHTML+'\n```\n':''}},
        {patterns:'img',isvoid:true,replacement:function(str,attrs,innerHTML){
            var src=attrs.match(attrRegExp('src')),alt=attrs.match(attrRegExp('alt')),title=attrs.match(attrRegExp('title'));
            return'!['+(alt&&alt[1]?alt[1]:'')+']'+'('+src[1]+(title&&title[1]?' "'+title[1]+'"':'')+')';}
        }
    ];
    for(var i=0,len=ELEMENTS.length;i<len;i++){
        if(typeof ELEMENTS[i].patterns==='string'){
            string=replaceEls(string,{tag:ELEMENTS[i].patterns,replacement:ELEMENTS[i].replacement,type:ELEMENTS[i].type});
            }
        else{
            for(var j=0,pLen=ELEMENTS[i].patterns.length;j<pLen;j++){
                string=replaceEls(string,{tag:ELEMENTS[i].patterns[j],replacement:ELEMENTS[i].replacement,type:ELEMENTS[i].type});
                }
            }
        }
        string=string.replace(/<.*?>/ig,'');
    function replaceEls(html,elProperties){
        var pattern=elProperties.isvoid?'<'+elProperties.tag+'\\b([^>]*)\\/?>':'<'+elProperties.tag+'\\b([^>]*)>([\\s\\S]*?)<\\/'+elProperties.tag+'>',regex=new RegExp(pattern,'gi'),markdown='';
        if(typeof elProperties.replacement==='string'){
            markdown=html.replace(regex,elProperties.replacement);
            }
        else{
            markdown=html.replace(regex,function(str,p1,p2,p3){
                return elProperties.replacement.call(this,str,p1,p2,p3);
                });
            }
        return markdown;
        }
    function attrRegExp(attr){
        return new RegExp(attr+'\\s*=\\s*["\']?([^"\']*)["\']?','i');
        }
    string=string.replace(/<pre\b[^>]*>`([\s\S]*)`<\/pre>/gi,function(str,innerHTML){
        innerHTML=innerHTML.replace(/^\t+/g,'  ');
        innerHTML=innerHTML.replace(/\n/g,'\n    ');
        return'\n\n    '+innerHTML+'\n';
        });
    string=string.replace(/^(\s{0,3}\d+)\. /g,'$1\\. ');
    var noChildrenRegex=/<(ul|ol)\b[^>]*>(?:(?!<ul|<ol)[\s\S])*?<\/\1>/gi;
    while(string.match(noChildrenRegex)){
        string=string.replace(noChildrenRegex,function(str){return replaceLists(str);});
        }
    function replaceLists(html){
        html=html.replace(/<(ul|ol)\b[^>]*>([\s\S]*?)<\/\1>/gi,function(str,listType,innerHTML){
            var lis=innerHTML.split('</li>');
            lis.splice(lis.length-1,1);
            for(i=0,len=lis.length;i<len;i++){
                if(lis[i]){
                    var prefix=(listType==='ol')?(i+1)+".  ":"*   ";
                    lis[i]=lis[i].replace(/\s*<li[^>]*>([\s\S]*)/i,function(str,innerHTML){
                        innerHTML=innerHTML.replace(/^\s+/,'');
                        innerHTML=innerHTML.replace(/\n\n/g,'\n\n    ');
                        innerHTML=innerHTML.replace(/\n([ ]*)+(\*|\d+\.) /g,'\n$1    $2 ');
                        return prefix+innerHTML;
                        });
                    }
                }
            return lis.join('\n');
            });
        return'\n\n'+html.replace(/[ \t]+\n|\s+$/g,'');
        }
    var deepest=/<blockquote\b[^>]*>((?:(?!<blockquote)[\s\S])*?)<\/blockquote>/gi;
    while(string.match(deepest)){
        string=string.replace(deepest,function(str){return replaceBlockquotes(str);});
        }
    function replaceBlockquotes(html){
        html=html.replace(/<blockquote\b[^>]*>([\s\S]*?)<\/blockquote>/gi,function(str,inner){
            inner=inner.replace(/^\s+|\s+$/g,'');
            inner=cleanUp(inner);
            inner=inner.replace(/^/gm,'> ');
            inner=inner.replace(/^(>([ \t]{2,}>)+)/gm,'> >');
            return inner;
            });
        return html;
        }
    function cleanUp(string){
        string=string.replace(/^[\t\r\n]+|[\t\r\n]+$/g,'');
        string=string.replace(/\n\s+\n/g,'\n\n');
        string=string.replace(/\n{3,}/g,'\n\n');
        return string;
        }
    return cleanUp(string);
    };
if(typeof exports==='object'){exports.toMarkdown=toMarkdown;}