How Many Backslashes Do I Need to Escape a Single Backslash in JavaScript Strings and Regular Expressions?

How to Escape Backslashes in Strings and Regular Expressions

In JavaScript, backslashes have special meanings within both regular expressions and string literals. To include an actual backslash character in either a string or regular expression, you must use double backslashes: .

Strings

To create a string that contains a single backslash, use two backslashes in the string literal:

var str = "\I have one backslash";

Regular Expressions

To create a regular expression that matches a single backslash, also use two backslashes in the regular expression pattern:

var rex = /\/;

Creating Regular Expressions from Strings

When creating a regular expression from a string, keep in mind that you're dealing with two levels: the string level and the regular expression level. To create a regular expression that matches a single backslash from a string, use four backslashes:

var rex = new RegExp("\\");

ES2015 and ES2018 Syntax

In recent JavaScript versions, you can use template literals and the String.raw function to simplify backslash escaping:

let str = String.raw`\apple`;

This will result in a string that contains the characters , a, p, p, l, and e. Note that you must avoid using ${ in template literals, as it starts a substitution.

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