index.js
function isNativeFunction(f) {
  if ((typeof f) !== 'function') {
    return false;
  }
  var exp = /^function\s+\w*\s*\(\s*\)\s*{\s+\[native code\]\s+}$/i;
  return exp.exec(Function.prototype.toString.call(f)) != null;
}
function isNativeFunction(f) {
  if ((typeof f) !== 'function') {
    return false;
  }
  var exp = /^function\s+\w*\s*\(\s*\)\s*{\s+\[native code\]\s+}$/i;
  return exp.exec(Function.prototype.toString.call(f)) != null;
}
function isNativeFunction ( f ) { if ( ( typeof f ) !== 'function' ) { return false ; } var exp = / ^function\s+\w*\s*\(\s*\)\s*{\s+\[native code\]\s+}$ / i ; return exp . exec ( Function . prototype . toString . call ( f ) ) != null ; }
Check if the given function is a native function
Check if the given function is a native function