# Array and Object Extensions

Negative-index access, aggregation, and existence checks added to `Array.prototype` and `Object.prototype`.

## Array

Source: `src/prototype/Array.ts`

| Method / Property | Description |
| --- | --- |
| `arr.$sum` | Sum of a numeric array via `reduce` |
| `arr.$shuffle` | In-place Fisher–Yates shuffle; returns `this` |
| `arr.$map` | A `Map` of `value → index` for every entry |
| `arr._(value, index?)` | Negative-index-aware insert (`splice`); appends when `index` is omitted |
| `arr.$(index)` | Negative-index-aware read |
| `arr.$i(target)` | `indexOf(target)`, returning `undefined` instead of `-1` |
| `arr.$_(index)` | Negative-index-aware removal (`splice`) |
| `arr.$$(target?)` | `true` if non-empty (no argument) or if `target` is present |
| `arr.$req(body)` | Joins the array as `/`-separated URL path segments, then calls `$req` on the resulting path |

## Object

Source: `src/prototype/Object.ts` (extends `Object.prototype`, so these apply to plain objects)

| Method / Property | Description |
| --- | --- |
| `obj.length` | `Object.keys(this).length` |
| `obj.$keys` / `obj.$values` | `Object.keys(this)` / `Object.values(this)` |
| `obj.$map` | Own enumerable entries as a `Map` |
| `obj.forEach(cb)` | Array-like iteration: `cb(key, value)` over own enumerable properties |
| `obj._(key, value, replace = true)` | Conditional setter — only overwrites an existing key when `replace` is `true` |
| `obj.$$(key?)` | `hasOwnProperty(key)` if `key` given, else `this.length > 0` |