In JavaScript, is there a way to iterate over the lexical tokens of a string?

Given this string, which I receive from an endpoint:

"\u0000\u0000\u0000\u001A%<some-random-text\fcdtoolHxxx1-34e3-4069-b97c-xxxxxxxxxxx\u001E\n" 

I would like to iterate the string to escape every sequence that starts with \u. The resulting string would be:

"\\u0000\\u0000\\u0000\\u001A%<some-random-text\fcdtoolHxxx1-34e3-4069-b97c-xxxxxxxxxxx\\u001E\n" 

Notice how \f and \n aren't escaped. So, how can I escape only those \u sequences?

Using a regular expression like this one, will not work, because the sequences \f and \n will also be replaced, but they should be untouched.

function escapeUnicode(str: string) { return s.replace(/[\u0000-\u001F]/gu, function (chr) { return "\\u" + ("0000" + chr.charCodeAt(0).toString(16)).slice(-4); }); } 

There's String.raw but unless you pass the string as a literal it won't work. For instance, in the code below using it as a literal I could do:

let s = String.raw`\u0000\u0000\u0000\u001A%<deployment-deploymentStepStart\fcdtoolHb3dccc41-8cf0-4069`; var escaped = String.raw``; for (let i = 0, j = i + 1; i < s.length - 1; i++,j=i+1) { let curChar = String.fromCharCode(s.charCodeAt(i)); let nextChar = String.fromCharCode(s.charCodeAt(j)); if (curChar === "\\" && nextChar === "u") { escaped += String.raw`\\u`; i++; } else { escaped += curChar; } } escaped += String.fromCharCode(s.charCodeAt(s.length - 1)); console.log(escaped); 

But as I mentioned above, the text comes from and endpoint, so if we store it in a variable and then try to do the same for loop it won't work.

let someVariable = "\u0000\u0000\u0000\u001A%<deployment-deploymentStepStart\fcdtoolHb3dccc41-8cf0-4069" let s = String.raw({raw: someVariable}); // ... rest of the code above