Add Properties names section (#75)

* Add properties names section

* Add time-span resource

* Fix watch files

docs/_sidebar.md

@@ -25,6 +25,7 @@
 * V8
 	* [Hidden Class](v8-tips/hidden-class.md)
 	* [Sparse Arrays](v8-tips/sparse-arrays.md)
+	* [Properties Names](v8-tips/properties-names.md)
 	* [Float Number](v8-tips/float-number.md)
 	* [Inline initialization](v8-tips/inline-initialization.md)
 	* [Monomorphic](v8-tips/monomorphic.md)

docs/resources.md

@@ -4,6 +4,7 @@
 
 * [tickedoff](https://github.com/jamiebuilds/tickedoff) – Use the faster timer function available for deferring something by a "tick".
 * [sliced](https://www.npmjs.com/package/sliced) – A faster Node.js alternative to `Array.prototype.slice.call(arguments)`.
+* [time-span](https://github.com/sindresorhus/time-span) – Simplified high resolution timing.
 
 ## Cache
 

docs/v8-tips/properties-names.md

@@ -0,0 +1,61 @@
+# Properties names
+
+When you use a unquoted property names as `Object` keys, the [specification](http://es5.github.io/x8.html#x8.10) defines that it will be implicitly serialized as `String`:
+
+```js
+var object = {
+  // `abc` is a valid identifier; no quotes are needed
+  abc: 1,
+  // `123` is a numeric literal; no quotes are needed
+  123: 2,
+  // `π` is a valid identifier; no quotes are needed
+  π: Math.PI,
+  // `var` is a valid identifier name (although it’s a reserved word); no quotes are needed
+  var: 4,
+  // `foo bar` is not a valid identifier name; quotes are required
+  'foo bar': 5,
+  // `foo-bar` is not a valid identifier name; quotes are required
+  'foo-bar': 6,
+  // the empty string is not a valid identifier name; quotes are required
+  '': 7
+}
+```
+
+When you use of numeric literals, the implicit coerced could be a bit confusing.
+
+For example, if you were to use the number `.12e3` as an (unquoted) property name, it would be coerced into a string first, and the actual object key would become `'120'`.
+
+```js
+var object = {
+  0.12e3: 'wut'
+}
+object[0.12e3] // 'wut'
+object['.12e3'] // undefined
+object['120'] // 'wut'
+```
+
+!>  A [numeric literal](http://es5.github.io/x7.html#x7.8.3) can be either a decimal literal (e.g. `0`, `123`, `123.`, `.123`, `1.23`, `1e23`, `1E-23`, `1e+23`, `12`, but not `01`, `+123` or `-123`) or a hex integer literal (0[xX][0-9a-fA-F]+ in regex, e.g. `0xFFFF`, `0X123`, `0xaBcD`).
+
+In this case, because the `String` representation of the `Number` is different, this is the correct way to acess using bracket notation:
+
+```js
+var object = {
+  12e34: 42
+}
+
+object['1.2e+35'] = 42
+```
+
+## Common Cases
+
+!> You can easily check the string value of any number with `String(number)` or [Unquoted JavaScript property name validator](https://mothereff.in/js-properties#12e34).
+
+This is a list of common object keys used as `String`:
+
+- `1` will be `'1'`.
+- `undefined` will be `'undefined'`.
+- `null` will be `'null'`.
+- `''` will be `''`.
+- `true`/`false` as `'true'`/`'false'`.
+
+Also, **reserverd words** cannot be used as object keys.

docs/v8-tips/sparse-arrays.md

@@ -12,9 +12,4 @@ If you want V8 to represent your `Array` in the `Fast Elements` form, you need t
 - Don't delete elements, specially in numeric `Array`s.
 - Don't load uninitialized or deleted elements.
 
-Another consideration: any name used as property name that is not a string is stringified via `.toString()`, so:
-
-- `1` will be `'1'`.
-- `undefined` will be `'undefined'`.
-- `null` will be `'null'`.
-- `''` will be `''`.
+Another consideration: any name used as property name that is not a `String` will be serialized, read more at [Properties Names](v8-tips/properties-names).

package.json

@@ -40,7 +40,7 @@
     "dev": "concurrently \"gulp\" \"npm run server:dev\"",
     "lint": "standard-markdown docs/**/*.md !docs/v8-tips/freeing-memory.md !docs/workflow/scope.md",
     "pretest": "npm run lint",
-    "server:dev": "cd docs && browser-sync start --server --files \"index.html, **/*.md main.min.js, style.min.css\"",
+    "server:dev": "cd docs && browser-sync start --server --files \"index.html, **/*.md, main.min.js, style.min.css\"",
     "test": "echo 'no tests yet' && exit 0"
   },
   "private": true,