将行注释（//）替换为块注释（/*）正则表达式 JS

Question

I want to get a regex to replace all line comments to block comments, but I want to return only legal js comments and not // that is part of a string for that I have to detect if // is in quotes and not replace it.

Now I got something like this /"(.*?\/\/.*?)"/ , but it replaces the opposite - all // in quotes and not the ones without.

// Change heading:

should match

document.getElementById("myH").innerHTML = "My First //Page";  

shouldn't match

document.getElementById("myP").innerHTML = "My first paragraph."; // Change paragraph:;

should match

console.log("some important info //shouldn't replace"); // this is important info

In this case, valid comment should match, but comment inside quotation marks shouldn't.

Answer 1

Match the comments with /(?:(?=["'][^"']*$)|(?=^[^"']*\/\/.*$))(.*?)\/\/(.*)/gm and replace with $1/*$2*/ .

 let code = `// Change heading: document.getElementById("myH").innerHTML = "My First Page"; document.getElementById("myP").innerHTML = "My first paragraph."; // Change paragraph: console.log("some important info //shouldn't replace"); // this is important info console.log('some important info //should not replace'); // this is important info`; code = code.replace(/(?:(?=["'][^"']*$)|(?=^[^"']*\/\/.*$))(.*?)\/\/(.*)/gm, "$1/*$2*/"); console.log(code);