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copied!<p>That's how the comparison operators work on objects:</p> <pre><code>var a = {}, b = {}; a === b; //false a == b; //false a > b; //false a < b; //false var c = { valueOf : function () { return 0; } }; var d = { valueOf : function () { return 1; } }; c === d; //false c == d; //false c > d; //false c < d; //true </code></pre> <h2>Under the hood</h2> <p>(sort of)</p> <h3>Part 1 : Equality</h3> <p>This is the easiest part. Both abstract equality (<code>==</code>, <a href="http://es5.github.com/#x11.9.3" rel="nofollow noreferrer">spec</a>) and strict equality (<code>===</code>, <a href="http://es5.github.com/#x11.9.6" rel="nofollow noreferrer">spec</a>) check if you're referring to the same object (sort of comparing references). In this case, they are obviously not, so they answer is <code>false</code> (<code>==</code> spec step 10, <code>===</code> spec step 7).</p> <p>Therefore, in both cases:</p> <pre><code>b1 == b2 //false b1 === b2 //false </code></pre> <h3>Part 2: The Comparison strikes back</h3> <p>Here comes the interesting part. Let's look at how the relational operators (<code><</code> and <code>></code>) <a href="http://es5.github.com/#x11.8.5" rel="nofollow noreferrer">are defined</a>. Let's follow the call chain in the two cases.</p> <pre><code>x = b1 //<Buffer aa> y = b2 //<Buffer ab> //11.8.5 The Abstract Relational Comparison Algorithm (http://es5.github.com/#x11.8.5) Let px be the result of calling ToPrimitive(x, hint Number). Let py be the result of calling ToPrimitive(y, hint Number). //9.1 ToPrimitive (http://es5.github.com/#x9.1) InputType is Object, therefore we call the internal [[DefaultValue]] method with hint Number. //8.12.8 [[DefaultValue]] (hint) http://es5.github.com/#x8.12.8 We try and fetch the object's toString method. If it's defined, call it. </code></pre> <p>And here we've reached the climax: What's a buffer's <code>toString</code> method? The answer lies deep inside node.js internals. If you want, <a href="https://github.com/joyent/node/blob/51f128d64b250dfeb128aab5117b5bbcd2cc51b5/lib/buffer.js#L389" rel="nofollow noreferrer">have at it</a>. What we can find out trivially is by experimentation:</p> <pre><code>> b1.toString() '�' > b2.toString() '�' </code></pre> <p>okay, that wasn't helpful. You'll notice that in the Abstract Relational Comparison Algorithm (what a big fancy name for <code><</code>), there's a step for dealing with strings. It just converts them to their numeric value - the char codes. Let's do that:</p> <pre><code>> b1.toString().charCodeAt(0) 65533 > b2.toString().charCodeAt(0) 65533 </code></pre> <p>65533 is an important number. It's the sum of two squares: <code>142^2 + 213^2</code>. It also happens to be the Unicode Replacement Character, a character signifying "I have no idea what happened". That's why its hexadecimal equivalent is FFFD.</p> <p>Obviously, <code>65533 === 65533</code>, so:</p> <pre><code>b1 < b2 //is b1.toString().charCodeAt(0) < b2.toString().charCodeAt(0) //is 65533 < 65533 //false b1 > b2 //following same logic as above, false </code></pre> <p>And that's that.</p> <h3>Dude, what the hell?</h3> <p>Okay, this must've been confusing since my efforts of explanation haven't been well thought through. To recap, here's what happened:</p> <ol> <li><p>You created a buffer. <a href="https://stackoverflow.com/users/1348195/benjamin-gruenbaum">Benjamin Gruenbaum</a> helped me recreate your test case by doing:</p> <p><code>var b1 = new Buffer([170]), b2 = new Buffer([171]);</code></p></li> <li><p>When outputting to console, the values are turned into their hex equivalent (see <a href="https://github.com/joyent/node/blob/51f128d64b250dfeb128aab5117b5bbcd2cc51b5/lib/buffer.js#L283" rel="nofollow noreferrer">Buffer#inspect</a>):</p> <p><code>170..toString(16) === 'aa'</code></p> <p><code>171..toString(16) === 'ab'</code></p></li> <li><p>However, internally, they represented invalid characters (since it's not hex encoding; again, you're free to delve into the implementation nitty gritty, I won't (oh the irony)). Therefore, when converted to a string, they were represented with the Unicode replacement character.</p></li> <li><p>Since they're different objects, any equality operator will return <code>false</code>.</p></li> <li><p>However, due to the way less-than and greater-than work, they were turned into strings (and then to numbers) for comparison. In light of point #3, that's the same value; therefore, they cannot be less-than or greater-than each other, leading to <code>false</code>.</p></li> </ol> <p>Finally, just to put a smile on your face:</p> <pre><code>b1 <= b2 //true b1 >= b2 //true </code></pre>

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