flattenReduceCallback
描述
¥Description
flattenReduce 的回调函数
¥Callback for flattenReduce
The first time the callback function is called, the values provided as arguments depend on whether the reduce method has an initialValue argument.
If an initialValue is provided to the reduce method:
-
The previousValue argument is initialValue.
-
The currentValue argument is the value of the first element present in the array.
If an initialValue is not provided:
-
The previousValue argument is the value of the first element present in the array.
-
The currentValue argument is the value of the second element present in the array.
定义
¥Definition
函数 (
¥function (
| 名称 | 类型 | 描述 |
|---|---|---|
| previousValue | Reducer | The accumulated value previously returned in the last invocation of the callback, or initialValue, if supplied. |
| currentFeature | 特性 | The current Feature being processed. |
| featureIndex | number | The current index of the Feature being processed. |
| multiFeatureIndex | number | The current index of the Multi-Feature being processed. |
)
返回
¥Returns
Reducer