index.js
function OptimizeCssnanoPlugin(options) {
  this.options = Object.assign({
    sourceMap: false,
    cssnanoOptions: {
      preset: 'default',
    },
  }, options);

  if (this.options.sourceMap) {
    this.options.sourceMap = Object.assign(
      {inline: false},
      this.options.sourceMap || {});
  }
}
function OptimizeCssnanoPlugin(options) {
  this.options = Object.assign({
    sourceMap: false,
    cssnanoOptions: {
      preset: 'default',
    },
  }, options);

  if (this.options.sourceMap) {
    this.options.sourceMap = Object.assign(
      {inline: false},
      this.options.sourceMap || {});
  }
}
function OptimizeCssnanoPlugin ( options ) { this . options = Object . assign ( { sourceMap : false , cssnanoOptions : { preset : 'default' , } , } , options ) ; if ( this . options . sourceMap ) { this . options . sourceMap = Object . assign ( { inline : false } , this . options . sourceMap || { } ) ; } }
Optimize cssnano plugin

@param {Object} options
Optimize cssnano plugin