如何在javascript中使用lookahead实现负面lookbehead？
问题描述：
由于您无法在JavaScript中使用负向倒序，因此如何使用超前或其他JavaScript支持的方法来实现相同的正则表达式匹配？如何在javascript中使用lookahead实现负面lookbehead？
(?<!<\/strong>\n\s{4}|<\/strong> \n\s{4})<br>
我试图找到不受</strong>和</strong> 后跟一个换行符等一系列空白字符的前导的<br>标签。
here's my code和一些示例文本进行测试。我使用pague来实现它，但我无法弄清楚如何使它在JavaScript中工作。
我已经尝试了其他例子，但我无法弄清楚如何根据我的需要实现这些解决方案。
答
的非正则表达式的方法
解析HTML时，我宁愿将HTML转换为DocumentFragments。这使我可以使用常用的querySelector方法和JS函数来实现我的最终目标。
我用以下代码替换了3个br标签：<div>REPLACED</div>。另外，为了创建片段，我使用了npm包html-fragment。
const html = `<p><strong>It was a weak bit.</strong>
<br>Because it’s already been done. If he had been like, “I don’t know, do you want to go to the La Brea tar pits and scoop some tar out and give ourselves a facial and burn ourselves and then only be able to know each other?” I would be like, “Haa, what?! Okay.” I mean, something new is going on here. He basically did the equivalent of like when guys do “fat guy in a little coat,” and they act like it’s not a Chris Farley callback. It’s like, this is a joke that’s in our system, so you’re a little bit unoriginal or even worse, you don’t know you’re unoriginal. </p>
<p><strong>Does he know it’s you?</strong>
<br>I do think he knew that I was a comedian named Jenny. So anyway, he’s like, “Let’s go to the Renaissance fair,” and I call my friends, and I’m like, “I’m not going on this date.” And they’re like, “Oh Jenny, come on, don’t be so closed down, you need to get out there.” I’m like, “UGH, fine.” Then we have a series of text messages back and forth that I’m just kind of like, <em>What is this? Is this what dating is like?</em> I was with my ex-husband for nine years, then I was in a very serious relationship that was passionate for a year, and I’m like, I don’t know, maybe I just don’t know what’s going on. And he’s asking me these questions that I’m like, What. The. Fuck. Why don’t you just wait?</p>
<p><strong>What is he asking you?</strong>
<br>Like, “Where was the last place you flew on an airplane?” And I’m not a rude or cruel woman, but I was like, I don’t... dude... just wait. Sit me down, I’ll tell you anything, just wait. Just wait until Saturday.</p>
<p><strong>Also, that’s the kind of question that is like, “I’m gonna go on the internet and search random questions to ask someone.”</strong>
<br>Yeah, it’s not great. It’s a real speed-dating question. I would love it in other circumstances if it was like a page in <em>Entertainment Weekly</em>, you know? So then I’m like, “I made us a reservation at this restaurant, will you meet me there?” He’s like, “Yes, is it fancy?” I’m like, “No,” and he’s like, “Okay, should I wear something like this?” And he sends me a picture of a knight’s costume. Like from the Renaissance fair. At which point I’m like what the fuck, dude? Because I didn’t even jump on this riff in the first place. It’s not like I was like, “Yes, and I will wear my wench's costume and bring a cup of mead!” I’m just like... Heh?! What? Why are you doing this?</p>
<p><strong>You didn’t respond positively to the bit.</strong>
<br>Never. Anyway, on the day of the date, I was like, “How will I know it’s you?” And I thought he would be like, “I’m 6’1” and I’ve got a beard,” or some
<p><br></p>
<p><br></p>
<p><br></p>`;
const fragment = HtmlFragment(html);
Array.from(fragment.querySelectorAll('br'))
.filter(br => {
let previous = br.previousElementSibling;
return (previous === null || previous.nodeName !== 'STRONG');
})
.forEach(br => {
let div = document.createElement('div');
div.innerText = 'REPLACED';
br.parentNode.replaceChild(div, br);
});
let div = document.createElement('div');
div.appendChild(fragment);
console.log(div.innerHTML);<script src="https://unpkg.com/[email protected]/lib/html-fragment.min.js"></script>+0
如果我要去那条路线，那么我宁愿只使用jquery或cheerio '$（'br'）。each（function（）{if（！$（this）.siblings（'strong' ））$（this）.remove（）}）'@ – selfagency
+0
@ selfagency，所以是一般的想法，然后删除br标签是唯一的孩子标签？ – KevBot
答
你必须匹配它才能通过它。
根本没有别的办法！
/(<\/strong>\n\s{4}|<\/strong> \n\s{4})?<br>/
在回调，如果组1不为空
https://regex101.com/r/xVJhGl/1
var text =
"<p><strong>It was a weak bit.</strong> \n"
+ " <br>Because it’s already been done. If he had been like, “I don’t know, do you want to go to the La Brea tar pits and scoop some tar out and give ourselves a facial and burn ourselves and then only be able to know each other?” I would be like, “Haa, what?! Okay.” I mean, something new is going on here. He basically did the equivalent of like when guys do “fat guy in a little coat,” and they act like it’s not a Chris Farley callback. It’s like, this is a joke that’s in our system, so you’re a little bit unoriginal or even worse, you don’t know you’re unoriginal. </p>\n"
+ "<p><strong>Does he know it’s you?</strong> \n"
+ " <br>I do think he knew that I was a comedian named Jenny. So anyway, he’s like, “Let’s go to the Renaissance fair,” and I call my friends, and I’m like, “I’m not going on this date.” And they’re like, “Oh Jenny, come on, don’t be so closed down, you need to get out there.” I’m like, “UGH, fine.” Then we have a series of text messages back and forth that I’m just kind of like, <em>What is this? Is this what dating is like?</em> I was with my ex-husband for nine years, then I was in a very serious relationship that was passionate for a year, and I’m like, I don’t know, maybe I just don’t know what’s going on. And he’s asking me these questions that I’m like, What. The. Fuck. Why don’t you just wait?</p>\n"
+ "<p><strong>What is he asking you?</strong> \n"
+ " <br>Like, “Where was the last place you flew on an airplane?” And I’m not a rude or cruel woman, but I was like, I don’t... dude... just wait. Sit me down, I’ll tell you anything, just wait. Just wait until Saturday.</p>\n"
+ "<p><strong>Also, that’s the kind of question that is like, “I’m gonna go on the internet and search random questions to ask someone.”</strong> \n"
+ " <br>Yeah, it’s not great. It’s a real speed-dating question. I would love it in other circumstances if it was like a page in <em>Entertainment Weekly</em>, you know? So then I’m like, “I made us a reservation at this restaurant, will you meet me there?” He’s like, “Yes, is it fancy?” I’m like, “No,” and he’s like, “Okay, should I wear something like this?” And he sends me a picture of a knight’s costume. Like from the Renaissance fair. At which point I’m like what the fuck, dude? Because I didn’t even jump on this riff in the first place. It’s not like I was like, “Yes, and I will wear my wench's costume and bring a cup of mead!” I’m just like... Heh?! What? Why are you doing this?</p>\n"
+ "<p><strong>You didn’t respond positively to the bit.</strong>\n"
+ " <br>Never. Anyway, on the day of the date, I was like, “How will I know it’s you?” And I thought he would be like, “I’m 6’1” and I’ve got a beard,” or some\n"
+ "<p><br></p>\n"
+ "<p><br></p>\n"
+ "<p><br></p>\n"
;
var rx = /(<\/strong>\n\s{4}|<\/strong> \n\s{4})?<br>/g;
text = text.replace(rx , function(match, a)
{
if (a)
return match;
return "<REPL>";
}
);
console.log(text);+0
谢谢。这也是我尝试在js vs. pcre中做到的最远的事情。我想这可能是我最好的选择，只需创建一个函数关闭.replace（）忽略这种情况下，而不是试图在正则表达式中完成。 – selfagency
+0
@selfagency - 发布一个示例用法。 – sln
[你尝试不匹配，你打算使用它的语言（https://regex101.com/r/ZactBT/2）。 –
是的，我在pcre之前创建它，然后才意识到我无法在js中使用相同的表达式。现在我试图将工作pcre代码转换为与js兼容的东西。 – selfagency
你想替换br's吗？ – KevBot