Acid3

John Resig - Acid 3 Tackles ECMAScript - Acid3 不只是 CSS test suite, 還包括了一堆的 ECMAScript test, source code 相當值得一看。

* Array Elisions - Making sure that stuff like [,,] doesn't have a length and [0,,1] has a length of 3.
* Array Methods - Doing an unshift with multiple arguments .unshift(0, 1, 2), joining with an undefined argument .join(undefined).
* Number Conversion - Banging against .toFixed(), .toExponential(), and .toPrecision() - especially with decimals and negative numbers.
* String Operations - Negative indicies in substr .substr(-7, 3), character access by index "foo"[1] (part of the ECMAScript 4 spec).
* Date - Making sure that certain method calls result in NaN results (like d.setMilliseconds(), with no arguments) and also enforcing +1900 year offsets.
* Unicode in Identifiers - You can't use escaped Unicode in identifiers, for example: eval("test.i\\u002b= 1;"); (that should throw an exception).
* Regular Expressions - /[]/ matches an empty set, /[])]/ should throw an exception, backreferences to non-existent captures, and negative lookaheads /(?!test)(test).exec("test test").
* Enumeration - Make sure that object properties are enumerated in the correct order, make sure that you're able to enumerate properties of certain names (toString, hasOwnProperty, etc.).
* Function Constructors - The user should be able to set custom constructors on the .constructor property, .constructor should not be enumerable, and .prototype.constructor should be deletable.
* Function Expressions - (function test(){ ... })(); You should be able to call the function by name, within the function itself, you can't directly overwrite the function name (only with a function-scoped variable), and 'test' isn't leaked into the parent scope.
* Exception Scope - Variables within the catch(){} should interact with the catch arguments primarily, followed by variables in an outer scope.
* Assignment Expressions - s = a.length = "123"; - a.length has a return value of 123 (the number) which is assigned to 's', rather than the correct result of the string "123".
* Encoding - encodeURI() and encodeURIComponent() must gracefully handle null bytes.