The JavaScript Raw String Method

In JavaScript, raw string literals let you handle strings that contain backslashes without interpreting them as escape characters. You access this via the String.raw() method, which is often used in regular expressions and file paths.

Understanding String.raw()

The String.raw() method returns a string where escape characters (like \\n for a new line) are ignored and treated as literal text. This is particularly useful when dealing with strings that include file paths or regular expressions where backslashes are prevalent.

Syntax of String.raw()

The syntax for String.raw() is straightforward:

String.raw(callSite, ...substitutions);

• callSite: Typically a template literal containing the desired string.
• substitutions: Values to be interpolated within the template literal.

Using String.raw() with template literals

Template literals are enclosed by the backtick ( ``) characters instead of single or double quotes, allowing embedded expressions called substitutions.

let filePath = String.raw`C:\\Development\\profile\\aboutme.html`;
console.log(filePath);
// Output: C:\\Development\\profile\\aboutme.html

Escaping in String.raw()

While String.raw() treats backslashes as literal characters, it’s important to note that it will not escape other characters unless a double backslash is used.

let text = String.raw`This is a backslash: \\\\\\nThis is not a new line.`;
console.log(text);
// Output: This is a backslash: \\\\\\nThis is not a new line.

Interpolation with String.raw()

You can use substitutions to insert values into the string:

let name = "World";
let greeting = String.raw`Hello, ${name}!`;
console.log(greeting);
// Output: Hello, World!

String.raw() as a tag function

String.raw() can also be used as a tag function for a template literal. In this context, it acts as a function that processes the template literal.

let name = "World";
let str = String.raw`Hi\\n${name}!`;
console.log(str);
// Output: Hi\\nWorld!

In the above example, \\n is not interpreted as a newline character but as a backslash followed by the letter 'n'.

Edge cases

Handling strings without substitutions or outside template literals:

let rawString = String.raw({ raw: 'test' }, 0, 1, 2);
console.log(rawString);
// Output: t0e1s2t

Here, String.raw() is called with an object that has a raw property, demonstrating its flexibility.

Common use cases

String.raw() is commonly used in situations where escape sequences are problematic:

• File system paths on Windows.
• Regular expressions where backslashes are necessary.
• When generating strings for other programming languages or command-line utilities.

How to use the raw value of a string

To use the raw value of a string, essentially bypassing escape sequences, you can pass a template literal directly to String.raw().

let rawText = String.raw`First line\\nSecond line`;
console.log(rawText);
// Output: First line\\nSecond line

This method ensures that the string is interpreted exactly as it's written, without processing escape sequences such as \\n for new line or \\t for tab.

Tips and best practices

• Always use String.raw() with template literals for consistent behavior.
• Remember that String.raw() does not escape single or double quotes.
• Utilize substitutions to simplify dynamic string generation.
• Use String.raw() judiciously to improve code readability when dealing with escape sequences.