remove lodash dependency

.nvmrc

@@ -0,0 +1 @@
+6

index.js

@@ -4,9 +4,7 @@
  */
 'use strict';
 
-var assign = require('lodash.assign');
-
-module.exports = assign(require('./lib/loader'), {
+module.exports = Object.assign(require('./lib/loader'), {
   moduleFilenameTemplate: require('./lib/module-filename-template'),
   codec                 : require('./codec')
 });

lib/loader.js

@@ -3,8 +3,7 @@
 var path = require('path');
 
 var loaderUtils = require('loader-utils'),
-    camelcase   = require('camelcase'),
-    defaults    = require('lodash.defaults');
+    camelcase   = require('camelcase');
 
 var PACKAGE_NAME = require('../package.json').name;
 
@@ -27,10 +26,11 @@ function loader(content, sourceMap) {
   // webpack 2: prefer loader options
   // webpack 3: deprecate loader.options object
   // webpack 4: loader.options no longer defined
-  var options = defaults(
-    {sep: path.sep},
+  var options = Object.assign(
+    {},
+    this.options && this.options[camelcase(PACKAGE_NAME)],
     loaderUtils.getOptions(this),
-    this.options && this.options[camelcase(PACKAGE_NAME)]
+    {sep: path.sep}
   );
 
   // process the source-map

lib/process/index.js

@@ -1,8 +1,6 @@
 'use strict';
 
-var assign    = require('lodash.assign'),
-    defaults  = require('lodash.defaults'),
-    camelcase = require('camelcase');
+var camelcase = require('camelcase');
 
 var debugMessage      = require('./debug-message'),
     toRegExp          = require('./to-reg-exp'),
@@ -17,21 +15,21 @@ var CODECS = require('../../codec');
 /**
  * Process the given source-map per the given options.
  * @param {{resourcePath:string, context:string, output:{path:string}}} context A loader or compilation
- * @param {{debug:boolean, fail:boolean, format:string|boolean, root:string, codecs:object}} options Options hash
+ * @param {{debug:boolean, fail:boolean, format:string|boolean, root:string, codecs:object}} opt Options hash
  * @param {object|string} sourceMapOrSource An incoming source-map or single source path
  * @returns {undefined|object|string} An amended source-map or source path else undefined
  */
-function process(context, options, sourceMapOrSource) {
+function process(context, opt, sourceMapOrSource) {
 
   // default options
-  defaults(options, {
+  var options = Object.assign({
     sep   : '/',
     debug : false,
     fail  : false,
     format: false,
     root  : false,
     codecs: CODECS
-  });
+  }, opt);
 
   // validate codecs
   var codecs = options.codecs
@@ -58,7 +56,7 @@ function process(context, options, sourceMapOrSource) {
     throwErrors(context.resourcePath, absoluteSources);
 
     // output map is a copy unless absent or we are removing
-    outputMap = (!inputMap || (options.format === 'remove')) ? undefined : assign({}, inputMap);
+    outputMap = (!inputMap || (options.format === 'remove')) ? undefined : Object.assign({}, inputMap);
 
     // some change in format
     if (options.format) {