test/mjsunit/instanceof.js

// Copyright 2008 the V8 project authors. All rights reserved.
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// modification, are permitted provided that the following conditions are
// met:
//
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assertTrue({} instanceof Object);
assertTrue([] instanceof Object);

assertFalse({} instanceof Array);
assertTrue([] instanceof Array);

function TestChains() {
  var A = {};
  var B = {};
  var C = {};
  B.__proto__ = A;
  C.__proto__ = B;

  function F() { }
  F.prototype = A;
  assertTrue(C instanceof F);
  assertTrue(B instanceof F);
  assertFalse(A instanceof F);

  F.prototype = B;
  assertTrue(C instanceof F);
  assertFalse(B instanceof F);
  assertFalse(A instanceof F);

  F.prototype = C;
  assertFalse(C instanceof F);
  assertFalse(B instanceof F);
  assertFalse(A instanceof F);
}

TestChains();


function TestExceptions() {
  function F() { }
  var items = [ 1, new Number(42), 
                true, 
                'string', new String('hest'),
                {}, [], 
                F, new F(),
                Object, String ];

  var exceptions = 0;
  var instanceofs = 0;

  for (var i = 0; i < items.length; i++) {
    for (var j = 0; j < items.length; j++) {
      try {
        if (items[i] instanceof items[j]) instanceofs++;
      } catch (e) {
        assertTrue(e instanceof TypeError);
        exceptions++;
      }
    }
  }
  assertEquals(10, instanceofs);
  assertEquals(88, exceptions);

  // Make sure to throw an exception if the function prototype
  // isn't a proper JavaScript object.
  function G() { }
  G.prototype = undefined;
  assertThrows("({} instanceof G)");
}

TestExceptions();