grunt-contrib-jshint requires *either* a jshintrc file or other options. I reject that dichotomy.

jshintrc-plus-grunt.js

'use strict';

module.exports = function (grunt) {

  var jshintrc = grunt.file.readJSON('.jshintrc');

  // super simple shallow copy/merge
  function merge(o1, o2) {
    var retVal = {}, i;
    for (i in o1) {
      retVal[i] = o1[i];
    }
    for (i in o2) {
      retVal[i] = o2[i];
    }
    return retVal;
  }

  // load grunt tasks
  grunt.loadNpmTask('grunt-contrib-jshint');

  // Project configuration.
  grunt.initConfig({

    jshint: {
      client: {
        src: ['public/js/**/*.js'],
        options: merge(jshintrc, {
          browser: true,
          globals: {
            jQuery: false
          }
        })
      },
      server: {
        src: ['Gruntfile.js', 'lib/**/*.js'],
        options: merge(jshintrc, {
          node: true
        })

      },
    },
  });

};