Preparation code

<script>
  var obj = {
    foo: 'bar',
    a: 'b',
    c: 'd',
    e: 'f'
  };
</script>

Test runner

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obj.hasOwnProperty('foo');
obj.hasOwnProperty('notthere');

obj['foo'] !== void 0;
obj['notthere'] !== void 0;

typeof obj['foo'] !== 'undefined';
typeof obj['notthere'] !== 'undefined';

'foo' in obj;
'notthere' in obj;

obj.foo !== void 0;
obj.notthere !== void 0;

typeof obj.foo !== void 0;
typeof obj.notthere !== void 0;

typeof obj['foo'] !== void 0;
typeof obj['notthere'] !== void 0;

!!obj['foo']
!!obj['notthere']

!!obj.foo;
!!obj.notthere;

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Revisions

You can edit these tests or add even more tests to this page by appending /edit to the URL. Here’s a list of current revisions for this page:

• Revision 1: published by Shane O'Sullivan on 1st September 2011
• Revision 2: published on 28th September 2011
• Revision 3: published on 14th October 2011
• Revision 4: published on 20th October 2011
• Revision 5: published on 20th October 2011
• Revision 6: published by Disturbed on 2nd November 2011
• Revision 7: published on 2nd November 2011
• Revision 8: published by 51L3N7 on 2nd November 2011
• Revision 9: published on 5th April 2012

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