fix: don't remove legal comments by default

src/index.js

@@ -41,7 +41,7 @@ class UglifyJsPlugin {
       exclude,
       uglifyOptions: {
         output: {
-          comments: false,
+          comments: extractComments ? false : /^\**!|@preserve|@license|@cc_on/,
         },
         ...uglifyOptions,
       },

test/__snapshots__/extract-comments-options.test.js.snap

@@ -1,83 +1,106 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
-exports[`errors 1`] = `Array []`;
+exports[`"options.extractComments" is "boolean" - "true": errors 1`] = `Array []`;
 
-exports[`errors 2`] = `Array []`;
+exports[`"options.extractComments" is "boolean" - "true": test.js 1`] = `"var foo=1;"`;
 
-exports[`errors 3`] = `Array []`;
+exports[`"options.extractComments" is "boolean" - "true": test1.js 1`] = `
+"/*! For license information please see test1.js.LICENSE */
+var foo=1;"
+`;
 
-exports[`errors 4`] = `Array []`;
+exports[`"options.extractComments" is "boolean" - "true": test1.js.LICENSE 1`] = `
+"/*! Legal Comment */
+"
+`;
 
-exports[`test.js 1`] = `"var foo=1;"`;
+exports[`"options.extractComments" is "boolean" - "true": warnings 1`] = `Array []`;
 
-exports[`test.js 2`] = `"var foo=1;"`;
+exports[`"options.extractComments" is "function": errors 1`] = `Array []`;
 
-exports[`test.js 3`] = `
+exports[`"options.extractComments" is "function": test.js 1`] = `
 "/*! For license information please see test.js.LICENSE */
 var foo=1;"
 `;
 
-exports[`test.js 4`] = `
-"/*! For license information please see test.js.LICENSE */
-var foo=1;"
+exports[`"options.extractComments" is "function": test.js.LICENSE 1`] = `
+"// Comment
+"
 `;
 
-exports[`test.js 5`] = `
+exports[`"options.extractComments" is "function": test1.js 1`] = `
 "/*! For license information please see test1.js.LICENSE */
 var foo=1;"
 `;
 
-exports[`test.js 6`] = `
+exports[`"options.extractComments" is "function": test1.js.LICENSE 1`] = `
+"/* Comment */
+"
+`;
+
+exports[`"options.extractComments" is "function": warnings 1`] = `Array []`;
+
+exports[`"options.extractComments" is "object": errors 1`] = `Array []`;
+
+exports[`"options.extractComments" is "object": test.js 1`] = `
 "/*! License information can be found in test.license.js */
 var foo=1;"
 `;
 
-exports[`test.js.LICENSE 1`] = `
+exports[`"options.extractComments" is "object": test.license.js 1`] = `
 "// Comment
 "
 `;
 
-exports[`test.js.LICENSE 2`] = `
-"// Comment
-"
-`;
+exports[`"options.extractComments" is "object": warnings 1`] = `Array []`;
 
-exports[`test.license.js 1`] = `
-"// Comment
-"
-`;
+exports[`"options.extractComments" is "regex": errors 1`] = `Array []`;
 
-exports[`test1.js 1`] = `"var foo=1;"`;
+exports[`"options.extractComments" is "regex": test.js 1`] = `"var foo=1;"`;
 
-exports[`test1.js 2`] = `
+exports[`"options.extractComments" is "regex": test1.js 1`] = `
 "/*! For license information please see test1.js.LICENSE */
 var foo=1;"
 `;
 
-exports[`test1.js 3`] = `
-"/*! For license information please see test1.js.LICENSE */
+exports[`"options.extractComments" is "regex": test1.js.LICENSE 1`] = `
+"// foo
+"
+`;
+
+exports[`"options.extractComments" is "regex": warnings 1`] = `Array []`;
+
+exports[`"options.extractComments" is "string": errors 1`] = `Array []`;
+
+exports[`"options.extractComments" is "string": test.js 1`] = `
+"/*! For license information please see test.js.LICENSE */
 var foo=1;"
 `;
 
-exports[`test1.js.LICENSE 1`] = `
-"// foo
+exports[`"options.extractComments" is "string": test.js.LICENSE 1`] = `
+"// Comment
 "
 `;
 
-exports[`test1.js.LICENSE 2`] = `
-"/* Comment */
-"
+exports[`"options.extractComments" is "string": test1.js 1`] = `
+"/*! For license information please see test1.js.LICENSE */
+var foo=1;"
 `;
 
-exports[`test1.js.LICENSE 3`] = `
+exports[`"options.extractComments" is "string": test1.js.LICENSE 1`] = `
 "/* Comment */
 "
 `;
 
-exports[`warnings 1`] = `Array []`;
+exports[`"options.extractComments" is "string": warnings 1`] = `Array []`;
+
+exports[`"options.extractComments" is not specify: errors 1`] = `Array []`;
 
-exports[`warnings 2`] = `Array []`;
+exports[`"options.extractComments" is not specify: test.js 1`] = `"var foo=1;"`;
 
-exports[`warnings 3`] = `Array []`;
+exports[`"options.extractComments" is not specify: test1.js 1`] = `
+"/*! Legal Comment */
+var foo=1;"
+`;
 
-exports[`warnings 4`] = `Array []`;
+exports[`"options.extractComments" is not specify: warnings 1`] = `Array []`;