In programming — especially in regular expressions (regex) and string handling — escaping metacharacters means treating special characters (like . or *) as literal symbols instead of their special meaning.
Let’s break it down clearly 👇
🔹 What Are Metacharacters?
Metacharacters are characters with special meanings in regex or string patterns.
For example, in regex, these are metacharacters:
. ^ $ * + ? ( ) [ ] { } | \ /
Each has a purpose, such as:
-
.→ matches any character -
^→ matches start of a string -
$→ matches end of a string -
*→ matches zero or more repetitions -
[]→ defines a character set
🔹 Escaping Metacharacters
To use a metacharacter as a literal character (not as a special one), you must escape it.
✅ Example (Regex)
let regex = /a\.b/;
console.log(regex.test("a.b")); // true
console.log(regex.test("acb")); // false
Here, the \. escapes the . so it matches an actual dot . instead of “any character”.
🔹 Escaping in JavaScript Strings
In JavaScript, the backslash \ is also an escape character inside strings — so you might need double escaping!
Example:
let regex = new RegExp("a\\.b"); // Double escape inside string
console.log(regex.test("a.b")); // true
🔹 Common Escapes
| Character | Escaped Version | Meaning |
|---|---|---|
. |
\. |
literal dot |
* |
\* |
literal asterisk |
? |
\? |
literal question mark |
+ |
\+ |
literal plus sign |
( |
\( |
literal open parenthesis |
[ |
\[ |
literal open bracket |
{ |
\{ |
literal open brace |
| ` | ` | | |
\ |
\\ |
literal backslash |
🔹 Practical Tip
If you want to escape all regex metacharacters in a string dynamically, you can use:
function escapeRegex(str) {
return str.replace(/[.*+?^${}()|[\]\\]/g, '\\$&');
}
console.log(escapeRegex("price is $5.99"));
// Output: "price is \$5\.99"
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