Template strings do not respect ascii_only option

[PurkkaKoodari]

I'm working with some modern JS code in an environment that doesn't handle control characters well, but the source code contains them in template strings. UglifyJS is outputting them raw even with ascii_only enabled.

Uglify version (uglifyjs -V)

uglify-js 3.19.1

JavaScript input

[`\0\f\x1f\u263a`, "\0\f\x1f\u263a"]

The uglifyjs CLI command executed or minify() options used.

npx uglifyjs --compress --output-opts ascii_only --comments UserScript --expression

JavaScript output or error produced.

(with non-printable bytes written out:)

[`<00><0c><1f>☺`,"\0\f\x1f\u263a"]

Potential solution

I think this would be solved by just adding to_utf8 calls to the output for AST_Template. It did resolve this in my local test, but I'm not familiar with the codebase.

UglifyJS/lib/output.js

Lines 1786 to 1798 in 2255074

	DEFPRINT(AST_Template, function(output) {
	var self = this;
	if (self.tag) self.tag.print(output);
	output.print("`");
	for (var i = 0; i < self.expressions.length; i++) {
	output.print(self.strings[i]);
	output.print("${");
	self.expressions[i].print(output);
	output.print("}");
	}
	output.print(self.strings[i]);
	output.print("`");
	});

     DEFPRINT(AST_Template, function(output) {
         var self = this;
         if (self.tag) self.tag.print(output);
         output.print("`");
         for (var i = 0; i < self.expressions.length; i++) {
-            output.print(self.strings[i]);
+            output.print(output.to_utf8(self.strings[i]));
             output.print("${");
             self.expressions[i].print(output);
             output.print("}");
         }
-        output.print(self.strings[i]);
+        output.print(output.to_utf8(self.strings[i]));
         output.print("`");
     });

[alexlamsl]

Interesting use case − I didn't think people using latest versions of ECMAScript would still be struggling with Unicode 😉

[PurkkaKoodari]

Interesting use case − I didn't think people using latest versions of ECMAScript would still be struggling with Unicode 😉

Unicode isn't a problem, but null bytes in source code aren't the favorite of certain software 😁

[alexlamsl]

Patch released in uglify-js@3.19.2