Great question! The issue you're running into is that when you use '\\' + char or template literals like \\${char}, you're creating a literal two-character string (a backslash followed by 'n') instead of the single line break character that JavaScript interprets as \n.

JavaScript doesn't have a built-in method exactly like String.applyBackslash(), but there are two straightforward ways to achieve what you want:

1. Use a Mapping Object (Most Control) #

Create an object that maps escape character identifiers to their actual JavaScript escape sequences. This lets you explicitly handle exactly the escape characters you need:

// Define common escape mappings
const escapeCharMap = {
  'n': '\n',
  't': '\t',
  'r': '\r',
  'b': '\b',
  'f': '\f',
  '\\': '\\'
};

const char = 'n';
// Get the corresponding escape sequence, or fallback to the original character
const result = escapeCharMap[char] || char;

console.log(result); // This will output an actual line break, not the string "\n"

2. Use JSON.parse (Quick and Concise) #

Leverage JSON.parse to handle the escape sequence parsing for you. JSON natively recognizes standard escape characters, so we can construct a valid JSON string and parse it:

const char = 'n';
// Construct a JSON string like "\"\\n\"", which parses to a newline
const result = JSON.parse(`"\\${char}"`);

console.log(result); // Also outputs an actual line break

Note that this method only works for escape sequences recognized by JSON (like n, t, r, etc.). It won't handle non-standard escape codes.

内容的提问来源于stack exchange，提问作者Hanz