module.exports = function(hljs) {
  return {
    aliases: ['js'],
    keywords: {
      keyword:
        'in of if for while finally var new function do return void else break catch ' +
        'instanceof with throw case default try this switch continue typeof delete ' +
        'let yield const export super debugger as async await',
      literal:
        'true false null undefined NaN Infinity',
      built_in:
        'eval isFinite isNaN parseFloat parseInt decodeURI decodeURIComponent ' +
        'encodeURI encodeURIComponent escape unescape Object Function Boolean Error ' +
        'EvalError InternalError RangeError ReferenceError StopIteration SyntaxError ' +
        'TypeError URIError Number Math Date String RegExp Array Float32Array ' +
        'Float64Array Int16Array Int32Array Int8Array Uint16Array Uint32Array ' +
        'Uint8Array Uint8ClampedArray ArrayBuffer DataView JSON Intl arguments require ' +
        'module console window document Symbol Set Map WeakSet WeakMap Proxy Reflect ' +
        'Promise'
    },
    contains: [
      {
        className: 'pi',
        relevance: 10,
        begin: /^\s*['"]use (strict|asm)['"]/
      },
      hljs.APOS_STRING_MODE,
      hljs.QUOTE_STRING_MODE,
      { // template string
        className: 'string',
        begin: '`', end: '`',
        contains: [
          hljs.BACKSLASH_ESCAPE,
          {
            className: 'subst',
            begin: '\\$\\{', end: '\\}'
          }
        ]
      },
      hljs.C_LINE_COMMENT_MODE,
      hljs.C_BLOCK_COMMENT_MODE,
      {
        className: 'number',
        variants: [
          { begin: '\\b(0[bB][01]+)' },
          { begin: '\\b(0[oO][0-7]+)' },
          { begin: hljs.C_NUMBER_RE }
        ],
        relevance: 0
      },
      { // "value" container
        begin: '(' + hljs.RE_STARTERS_RE + '|\\b(case|return|throw)\\b)\\s*',
        keywords: 'return throw case',
        contains: [
          hljs.C_LINE_COMMENT_MODE,
          hljs.C_BLOCK_COMMENT_MODE,
          hljs.REGEXP_MODE,
          { // E4X / JSX
            begin: /</, end: />\s*[);\]]/,
            relevance: 0,
            subLanguage: 'xml'
          }
        ],
        relevance: 0
      },
      {
        className: 'function',
        beginKeywords: 'function', end: /\{/, excludeEnd: true,
        contains: [
          hljs.inherit(hljs.TITLE_MODE, {begin: /[A-Za-z$_][0-9A-Za-z$_]*/}),
          {
            className: 'params',
            begin: /\(/, end: /\)/,
            excludeBegin: true,
            excludeEnd: true,
            contains: [
              hljs.C_LINE_COMMENT_MODE,
              hljs.C_BLOCK_COMMENT_MODE
            ]
          }
        ],
        illegal: /\[|%/
      },
      {
        begin: /\$[(.]/ // relevance booster for a pattern common to JS libs: `$(something)` and `$.something`
      },
      {
        begin: '\\.' + hljs.IDENT_RE, relevance: 0 // hack: prevents detection of keywords after dots
      },
      // ECMAScript 6 modules import
      {
        beginKeywords: 'import', end: '[;$]',
        keywords: 'import from as',
        contains: [
          hljs.APOS_STRING_MODE,
          hljs.QUOTE_STRING_MODE
        ]
      },
      { // ES6 class
        className: 'class',
        beginKeywords: 'class', end: /[{;=]/, excludeEnd: true,
        illegal: /[:"\[\]]/,
        contains: [
          {beginKeywords: 'extends'},
          hljs.UNDERSCORE_TITLE_MODE
        ]
      }
    ],
    illegal: /#/
  };
};