JavaScript字符串匹配方法快速指南

String.prototype.match() (aka: the match method on strings) can allow you to switch out strings or set conditions if a string or any data is matched. It then stores that data in a new array.

String.prototype.match() (又名：字符串的match方法)可以让您在匹配字符串或任何数据时切换出字符串或设置条件。然后，它将数据存储在新数组中。

First the syntax and then the explanation:

首先是语法，然后是解释：

let newArray = string.match(condition);

术语 (Terminology)

The string match() method will return an array with the items being matches from a provided regular expression found in the string. You can read more about regular expressions in JavaScript here.

字符串match()方法将返回一个数组，其中的项与字符串中提供的regular expression的项匹配。您可以在此处阅读有关JavaScript中正则表达式的更多信息。

Remember, when all conditions are matched, those results will be stored in a new array.

请记住，当所有条件都匹配时，这些结果将存储在新数组中 。

Take the following example:

请看以下示例：

const intro = "Hello Alligators, Hello Devs, how are you?"

const regex = /Hello/g;

const greeting = intro.match(regex);

The above will give us an array like this: ["Hello", "Hello"]. This works fine if we know the exact string we’re looking to match, but what about dynamic content or an actual use case?

上面的代码将给我们这样的数组： ["Hello", "Hello"] 。如果我们知道要查找的确切字符串，则此方法很好，但是动态内容或实际用例呢？

Here’s a simple example that finds repeated letters in a string:

这是一个简单的示例，可在字符串中查找重复的字母：

const str = 'See you later, Alligator! Not so soon baboon!';
const matches = str.match(/([a-z])\1+/gi);

console.log('H' + matches.join(""));
// "Heelloooo"

Though these are simple examples, the deeper you learn about regular expressions, the more powerful this string method becomes. The simple use of i for insensitive case allows the match method to highlight more entries.

尽管这些都是简单的示例，但是您对正则表达式的了解越深，这种字符串方法就越强大。不区分大小写的i的简单用法允许match方法突出显示更多条目。

The match method has 3 modes…

匹配方法有3种模式…

1st: If the g(global) flag is used for your RegEx, you’ll get all results stored in an array.
1st ：如果将g (全局)标志用于RegEx，则将所有结果存储在数组中。
2nd: If there are no g flag used, the first match will return an array with keys/values sharing index of the first matched expression, the full input and then the capturing groups. In other words, the same result as with using RegExp.exec().
2nd ：如果没有使用g标志，则第一个匹配项将返回一个数组，该数组包含第一个匹配表达式的键/值共享索引，完整输入以及捕获组。换句话说，与使用RegExp.exec()结果相同。

let newYear = "Happy New Year";
let results = newYear.match(/new/i);
// [ 'New', index: 6, input: 'Happy New Year', groups: undefined ]

3rd: If there’s no match, the method returns null, or, with the following code, an empty array:
3rd ：如果不匹配，则该方法返回null ，或者使用以下代码返回一个空数组：

let results = newYear.match(regex) || [];

结论 (Conclusion)

Match is a fun little method that can be used in a lot of creative ways like pulling out keywords from a paragraph or replacing words if the condition matches the regex. Take the time to learn about Regular Expressions in JavaScript. It’ll make match even more useful for you.

匹配是一种有趣的小方法，可用于许多创造性方式，例如从段落中提取关键字或在条件与正则表达式匹配时替换单词。花时间学习JavaScript中的正则表达式。它会使匹配对您更有用。

翻译自: https://www.digitalocean.com/community/tutorials/js-string-match