使用正则表达式从 HTML 中提取文本和链接

发布于 2024-08-17 02:40:29 字数 578 浏览 5 评论 0原文

我想从 html 文档中提取文本，并将链接保留在其中。例如：

从这个 HTML 代码中

<div class="CssClass21">bla1 bla1 bla1 <a href="http://www.ibrii.com">go to ibrii</a> bla2 bla2 bla2 <img src="http://www.contoso.com/hello.jpg"> <span class="cssClass34">hello hello</span>

，我想提取这个

bla1 bla1 bla1 <a href="http://www.ibrii.com">go to ibrii</a> bla2 bla2 bla2 hello hello

在 StackOverflow 上的另一篇文章中，我找到了 RegEx <[^>]*> ，它允许通过替换每个匹配来提取文本什么也没有。如何从匹配中排除锚标记？看来正则表达式不允许反向匹配。

原文

I would like to extract text from an html document keeping the links inside it. for example:

From this HTML code

<div class="CssClass21">bla1 bla1 bla1 <a href="http://www.ibrii.com">go to ibrii</a> bla2 bla2 bla2 <img src="http://www.contoso.com/hello.jpg"> <span class="cssClass34">hello hello</span>

I would like to extract just this

bla1 bla1 bla1 <a href="http://www.ibrii.com">go to ibrii</a> bla2 bla2 bla2 hello hello

In another post on StackOverflow i have found the RegEx <[^>]*> which allows to extract text by replacing every match with nothing. How can I exclude the anchor tags from the match? It seems that RegEx do not allow inverse matching.

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零時差 2024-08-24 02:40:30

暂时将 ... 编码为其他内容，删除所有其他标签，然后恢复标签：

// Example in javascript:
string.
    replace(/<a(.*?)>/g,'\0$1\0').
    replace(/<\/a>/,'\1').
    replace(/<[^>]*>/,'').
    replace(/\0(.*?)\0/,'<a$1>').
    replace(/\1/,'</a>');

在上面的代码中，我使用 NUL 和 SOH 字符（ASCII 0x00 和 0x01）作为标记的替换，只是因为它们不太可能出现在字符串中。请随意将它们替换为不会出现在字符串中的任何其他字符或字符序列。

从其他评论来看，您似乎正在浏览器中操作。在这种情况下，浏览器已经为您将 HTML 解析为漂亮的 DOM 树。使用 DOM 方法解析树并按照您想要的方式处理它：

function simpleHTML (domNode) {
    var ret = "";
    if (domNode.nodeType === Node.ELEMENT_NODE) {
        var children = domNode.childNodes;
        for (var i=0;i<children.length;i++) {
            var child = children[i];

            // Filter out unwanted nodes to speed up processing.
            // For example, you can ignore 'SCRIPT' nodes etc.
            if (child.nodeName != 'SCRIPT') {
                if (child.nodeName == 'A') {
                    ret += '<a href="' + child.href + '">' +
                               simpleHTML(child) +
                           '</a>';
                }
                else {
                    ret += simpleHTML(child);
                }
            }
        }
    }
    else if (domNode.nodeType === Node.TEXT_NODE) {
        ret +=  domNode.nodeValue;
    }
    return ret;
}
// serialize the whole document:
var simpleDocument = simpleHTML(document.body);

// serialize a div:
var simpleDiv = simpleHTML(document.getElementById('some_div'));

// filter a html formatted string:
var temp = document.createElement('DIV');
temp.innerHTML = original_string;
simple_string = simpleHTML(temp);

Temporarily encode <a href ...>...</a> into something else, remove all other tags then restore the <a> tags:

// Example in javascript:
string.
    replace(/<a(.*?)>/g,'\0$1\0').
    replace(/<\/a>/,'\1').
    replace(/<[^>]*>/,'').
    replace(/\0(.*?)\0/,'<a$1>').
    replace(/\1/,'</a>');

In the code above I use the NUL and SOH characters (ASCII 0x00 and 0x01) as replacements for <a> tags simply because it is highly unlikely that they would appear in strings. Feel free to replace them with any other character or sequence of characters that would not appear in your string.

From additional comments it appears you're operating in a browser. In which case the browser has already parsed the HTML for you into a nice DOM tree. Use DOM methods to parse through the tree and process it the way you want:

function simpleHTML (domNode) {
    var ret = "";
    if (domNode.nodeType === Node.ELEMENT_NODE) {
        var children = domNode.childNodes;
        for (var i=0;i<children.length;i++) {
            var child = children[i];

            // Filter out unwanted nodes to speed up processing.
            // For example, you can ignore 'SCRIPT' nodes etc.
            if (child.nodeName != 'SCRIPT') {
                if (child.nodeName == 'A') {
                    ret += '<a href="' + child.href + '">' +
                               simpleHTML(child) +
                           '</a>';
                }
                else {
                    ret += simpleHTML(child);
                }
            }
        }
    }
    else if (domNode.nodeType === Node.TEXT_NODE) {
        ret +=  domNode.nodeValue;
    }
    return ret;
}
// serialize the whole document:
var simpleDocument = simpleHTML(document.body);

// serialize a div:
var simpleDiv = simpleHTML(document.getElementById('some_div'));

// filter a html formatted string:
var temp = document.createElement('DIV');
temp.innerHTML = original_string;
simple_string = simpleHTML(temp);

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