escape all (not-already-escaped) double-quote chars in a string

gistfile1.js

// NOTE: only escapes a " if it's not already escaped
function escapeDoubleQuotes(str) {
	return str.replace(/\\([\s\S])|(")/g,"\\$1$2"); // thanks @slevithan!
}

escapeDoubleQuotes(`ab`);          // ab  =>  ab           (nothing escaped)
escapeDoubleQuotes(`a"b`);         // a"b  =>  a\"b
escapeDoubleQuotes(`a\\"b`);       // a\"b  =>  a\"b       (nothing escaped)
escapeDoubleQuotes(`a\\\\"b`);     // a\\"b  =>  a\\\"b
escapeDoubleQuotes(`a\\\\\\"b`);   // a\\\"b  =>  a\\\"b   (nothing escaped)

escapeDoubleQuotes(`a"b"c`);       // a"b"c  =>  a\"b\"c
escapeDoubleQuotes(`a""b`);        // a""b  =>  a\"\"b
escapeDoubleQuotes(`""`);          // ""  =>  \"\"

// don't unnecessarily escape:
escapeDoubleQuotes(escapeDoubleQuotes(escapeDoubleQuotes(`a"b`)));  // a"b  =>  a\"b

When you need to use both single and double quotes in the string you can use the following solutions to escape the quotes:

• " becomes "
• ' becomes '

Keep in mind that you will never need to escape more than the following five special characters:

• & becomes &
• < becomes <
• becomes >
• " becomes "
• ' becomes '

Once you have these escaped you should never have an issue with broken values in HTML again.

Reference: https://jamilhallal.blogspot.com/2022/04/javascript-escape-quotes.html