Wildcard: .
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A wildcard matches all characters except line terminators. It also matches line terminators if the s flag is set.
Syntax#
.
Description#
. matches any character except line terminators. If the s flag is set, . also matches line terminators.
The exact character set matched by . depends on whether the regex is Unicode-aware. If it is Unicode-aware, . matches any Unicode code point; otherwise, it matches any UTF-16 code unit. For example:
/../.test("😄"); // true; matches two UTF-16 code units as a surrogate pair
/../u.test("😄"); // false; input only has one Unicode character
Examples#
Usage with quantifiers#
Wildcards are often used with quantifiers to match any character sequence, until the next character of interest is found. For example, the following example extracts the title of a Markdown page in the form # Title:
function parseTitle(entry) {
// Use multiline mode because the title may not be at the start of
// the file. Note that the m flag does not make . match line
// terminators, so the title must be on a single line
// Return text matched by the first capturing group.
return /^#[ \t]+(.+)$/m.exec(entry)?.[1];
}
parseTitle("# Hello world"); // "Hello world"
parseTitle("## Subsection"); // undefined
parseTitle(`
---
slug: Web/JavaScript/Reference/Regular_expressions/Wildcard
---
# Wildcard: .
A **wildcard** matches all characters except line terminators.
`); // "Wildcard: ."
Matching code block content#
The following example matches the content of a code block enclosed by three backticks in Markdown. It uses the s flag to make . match line terminators, because the content of a code block may span multiple lines:
function parseCodeBlock(entry) {
return /^```.*?^(.+?)\n```/ms.exec(entry)?.[1];
}
parseCodeBlock(`
\`\`\`js
console.log("Hello world");
\`\`\`
`); // "console.log("Hello world");"
parseCodeBlock(`
A \`try...catch\` statement must have the blocks enclosed in curly braces.
\`\`\`js example-bad
try
doSomething();
catch (e)
console.log(e);
\`\`\`
`); // "try\n doSomething();\ncatch (e)\n console.log(e);"
[!WARNING] These examples are for demonstration only. If you want to parse Markdown, use a dedicated Markdown parser because there are many edge cases to consider.
Specifications#
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Browser compatibility#
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