Add quirks doc

kgryte · kgryte · commit a412e9dc8b34 · 2017-11-16T16:31:10.000-08:00
diff --git a/docs/javascript_quirks.md b/docs/javascript_quirks.md
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+# JavaScript Quirks
+
+> A list of JavaScript quirks which should be kept in mind when writing implementations.
+
+## Rounding
+
+1.  The JavaScript standard ([ECMA-262][ecma-262-math-round]) defines the behavior of `Math.round` such that "ties" (e.g., `1.5` and `-1.5`) are rounded toward `+infinity`.
+
+    ```javascript
+    var x = Math.round( 1.5 );
+    // returns 2.0
+
+    x = Math.round( -1.5 );
+    // returns -1.0
+    ```
+
+    This behavior is relatively uncommon among languages implementing a round operation for floating-point numbers and appears to have originated by following [Java][java-math-round].
+
+    When implementing lower-level math functions which may require rounding, exercise caution when considering whether the built-in rounding behavior is appropriate and ensure that bias is not introduced in computed results.
+
+
+<section class="links">
+
+[ecma-262-math-round]: http://www.ecma-international.org/ecma-262/6.0/#sec-math.round
+
+[java-math-round]: https://docs.oracle.com/javase/7/docs/api/java/lang/Math.html#round%28double%29
+
+</section> 
