Function timing

timing(): () => number
Create a high-resolution performance timer.

创建一个高精度性能计时器。

Returns () => number
A function that returns the elapsed milliseconds since the timer was created. The returned function can be called multiple times, each time returning the elapsed time from the original creation point.

返回一个函数，该函数返回自计时器创建以来经过的毫秒数。返回的函数可以多次调用，每次返回自创建点以来的经过时间。
Remarks
Uses performance.now() for sub-millisecond precision. Falls back to Date.now() if performance is not available in the runtime.

使用 performance.now() 实现亚毫秒级精度。如果运行时没有 performance，则回退到 Date.now()。
Example
```
const timer = timing()
// ... do some work ...
const elapsed = timer() // e.g. 1.234
```
Example
Measure multiple checkpoints:
```
const timer = timing()
doSomething()
const t1 = timer() // time after doSomething
doSomethingElse()
const t2 = timer() // total time including doSomethingElse
```
- Defined in src/util/timing.ts:38