Documentation / @ripl/charts / createIndexLookup
Function: createIndexLookup() ​
createIndexLookup<
TValue>(values): (value) =>number
Defined in: charts/src/core/data.ts:58
Builds a value → index lookup with Array.prototype.indexOf semantics: the earliest occurrence wins for a duplicated value, an absent value resolves to -1, and NaN matches nothing.
A render loop that resolves each datum's position with indexOf is quadratic over a series; building the lookup once makes every resolution constant time.
Type Parameters ​
| Type Parameter | Description |
|---|---|
TValue | The array's element type. |
Parameters ​
| Parameter | Type | Description |
|---|---|---|
values | readonly TValue[] | The array to index, in order. |
Returns ​
A function resolving a value to its index in values, or -1 when absent.
(value) => number