javascript - 从 url javascript 中提取域名

Question

我正在尝试从“tweets”中的字符串中提取域名，如何避免从字符串中提取双反斜杠？我在 let url 中定义的正则表达式

let tweets = [
  "Thank you to the Academy and the incredible cast & crew of #TheRevenant. #Oscars",
  "@HardingCompSci department needs student volunteers for #HourOfCode https://hourofcode.com/us",
  "Checkout the most comfortable earbud on #Kickstarter and boost your #productivity https://www.kickstarter.com/",
  "Curious to see how #StephenCurry handles injury. http://mashable.com/2016/04/25/steph-curry-knee-injury-cries-cried/"
];


let url = /\/\/.+?\.com?/;

tweets.forEach(function(tweet) {
  console.log(url.exec(tweet));
});

Answer 1

使用Capturing Group

A part of a pattern can be enclosed in parentheses (...). This is called a “capturing group”.

That has two effects:

It allows to get a part of the match as a separate item in the result array.If we put a quantifier after the parentheses, it applies to the parentheses as a whole.

在你的代码中你有 let url =/\/\/.+?\.com?/;

您只对 2 个斜线之后的部分感兴趣，因此通过将其括在大括号中来为其创建一个捕获组:let url =/\/\/(.+?\.com?)/;

然后稍微更改循环中的代码以从第一个捕获组中获取结果，最终得到:

let tweets = [
  "Thank you to the Academy and the incredible cast & crew of #TheRevenant. #Oscars",
  "@HardingCompSci department needs student volunteers for #HourOfCode https://hourofcode.com/us",
  "Checkout the most comfortable earbud on #Kickstarter and boost your #productivity https://www.kickstarter.com/",
  "Curious to see how #StephenCurry handles injury. http://mashable.com/2016/04/25/steph-curry-knee-injury-cries-cried/"
];


let url = /\/\/(.+?\.com?)/;

tweets.forEach(function(tweet) {
  var match = url.exec(tweet)
  console.log(match && match[1] || match);
});