Microsoft.AspNet.Web.Optimization JavaScript bundling fails to minify template literals

Question

Using the latest version of Microsoft.AspNet.Web.Optimization v1.1.3 I am unable to get bundling to minify the JavaScript if it includes template literals. For example if I include the following in one of my bundle scripts:

var name = 'Bob';
var formattedName = `${name} says hello`;

The resulting bundle will join all files but it won't minify code, and gives me this error:

/* Minification failed. Returning unminified contents.
(2,13-14): run-time error JS1014: Invalid character: `
(2,15-16): run-time error JS1004: Expected ';': {
(2,30-31): run-time error JS1014: Invalid character: `
(3,1-2): run-time error JS1107: Expecting more source characters
*/

I understand this feature was only introduced in ECMAScript2015 and it's clearly not supported but is there a clean workaround other than reverting back to the old string concatenation methods?

var name = 'Bob';
var formattedName = name + ' says hello';

Also, will template literal support go into future versions of Microsoft.AspNet.Web.Optimization?

Answer 1

I am using the bundleconfig.json method for minifying some script files and I encountered similar errors when running the appropriate task:

Illegal assignment: =
Expected ';'
Expected ';'
Expected expression
Expected '}'

I managed to change the literal from this:

style.textContent = `
...
`;

To this:

style.textContent = `
...`;

It will probably not answer your specific question (as you used Gulp), but might help someone out there, that doesn't want to start using npm's various packages for the same objective.