How to call native es6 template string replacement from tag function?

Question

I\'m writing a es6 tag function for template literals, which first checks a condition in the string and, if the condition isn\'t found, merely interprets the template litera

Answer 1

There is no such builtin function - untagged template literals are just evaluated straight to strings.

is there a faster way?

That depends a lot on the implementation. In case you are using a transpiler, I would avoid using rest parameters, iterators and for of loops:

function template(strs) {
    var result = strs[0];
    for (var i=1; i < strs.length; i++) {
        result += arguments[i];
        result += strs[i];
    }
    return result;
}

Answer 2

You can (ab)use String.raw (the only built-in tag) for this purpose:

function doNothingTag() {
  arguments[0] = { raw: arguments[0] };
  return String.raw(...arguments);
}

doNothingTag`It works!`
// "It works!"

doNothingTag`Even\nwith\nescape\nsequences!`
// "Even
// with
// escape
// sequences!"

This is essentially just tricking String.raw into thinking that the escape-interpreted string is the raw version.