JavaScript Escape Sequences


Not everything that starts with a backslash is an escape sequence. Many characters are just not useful to escape sequences, and will simply cause a preceding backslash to be ignored.

"\H\e\l\l\o" === "Hello" // true

On the other hand, some characters like "u" and "x" will cause a syntax error when used improperly after a backslash. The following is not a valid string literal because it contains the Unicode escape sequence prefix \u followed by a character that is not a valid hexadecimal digit nor a curly brace:

"C:\Windows\System32\updatehandlers.dll" // SyntaxError

A backslash at the end of a line inside a string does not introduce an escape sequence, but indicates line continuation, i.e.

uation" === "continuation" // true

Similarity to other formats

While escape sequences in JavaScript bear resemblance to other languages and formats, like C++, Java, JSON, etc. there will often be critical differences in the details. When in doubt, be sure to test that your code behaves as expected, and consider checking the language specification.