_baseIsNative.js

var isFunction = require('./isFunction'),
    isMasked = require('./_isMasked'),
    isObject = require('./isObject'),
    toSource = require('./_toSource');

/**
 * Used to match `RegExp`
 * [syntax characters](http://ecma-international.org/ecma-262/7.0/#sec-patterns).
 */
var reRegExpChar = /[\\^$.*+?()[\]{}|]/g;

/** Used to detect host constructors (Safari). */
var reIsHostCtor = /^\[object .+?Constructor\]$/;

/** Used for built-in method references. */
var funcProto = Function.prototype,
    objectProto = Object.prototype;

/** Used to resolve the decompiled source of functions. */
var funcToString = funcProto.toString;

/** Used to check objects for own properties. */
var hasOwnProperty = objectProto.hasOwnProperty;

/** Used to detect if a method is native. */
var reIsNative = RegExp('^' +
  funcToString.call(hasOwnProperty).replace(reRegExpChar, '\\$&')
  .replace(/hasOwnProperty|(function).*?(?=\\\()| for .+?(?=\\\])/g, '$1.*?') + '$'
);

/**
 * The base implementation of `_.isNative` without bad shim checks.
 *
 * @private
 * @param {*} value The value to check.
 * @returns {boolean} Returns `true` if `value` is a native function,
 *  else `false`.
 */
function baseIsNative(value) {
  if (!isObject(value) || isMasked(value)) {
    return false;
  }
  var pattern = isFunction(value) ? reIsNative : reIsHostCtor;
  return pattern.test(toSource(value));
}

module.exports = baseIsNative;