javascript regular expression to delete empty lines

In JavaScript, using regular expressions to delete empty lines is a very common operation. This operation is useful in tasks such as processing text, cleaning data, etc., because blank lines often appear in text, and they can be easily removed using regular expressions.

The following will introduce how to use regular expressions to delete blank lines.

What is a regular expression?

Regular Expression (Regular Expression) is a grammatical rule used to describe character patterns. It is a very powerful tool that can help us match, find, and replace strings.

Use regular expressions to delete empty lines

The regular expression to delete empty lines is very simple, you only need to match any content between two
empty lines, in the matched content Add a newline character before and after to delete this empty line.

The following is the specific code implementation:

let str = "这是第一行

这是第三行
这是第四行

这是第六行

这是第八行";
let result = str.replace(/^
+|
+$/g, '');
console.log(result);

In this code, we use the replace() function to replace the matched content with an empty string to delete empty lines the goal of. The specific regular expression is: /^
|
$/g

This regular expression contains two parts:

1. /^
   /: Indicates matching one or more newline characters (
   ) at the beginning of the string.
2. /
   $/g: Indicates matching one or more newline characters (
   ) at the end of the string.

The meaning of this regular expression is to replace the newline characters at the beginning and end of the string with empty strings, and then delete empty lines.

It should be noted that this regular expression needs to use the newline character (
) for matching. If the text uses the CRLF newline character of the Windows system, you need to replace the ## in the regular expression. Replace # with
.

Here is a code example for handling CRLF newlines:

let str = "这是第一行

这是第三行
这是第四行

这是第六行

这是第八行";
let result = str.replace(/^
+|
+$/g, '');
console.log(result);

Summary

In JavaScript, removing empty lines is very simple using regular expressions. Just use a regular expression to match, and then use the replace() function to replace the matched content with an empty string, and you can delete the empty lines.

It should be remembered that regular expressions are only suitable for processing plain text data and cannot be used to process data in specific formats such as HTML tags. Also, pay attention to the type of line breaks used in the text.

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