What is the type of a continuous numeric d3.scaleLinear() scale in typescript

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I am passing d3 linear scales into a function using typescript.

import {scaleLinear} from 'd3-scale'

const myScale = scaleLinear().domain([0,10]).range([0,1])

const myFunc = (myScale : ScaleLinear<what, where, why>) => {
//draw something
}

I looked at @types d3 scale documentation and found this line


export interface ScaleLinear<Range, Output, Unknown = never> extends ScaleContinuousNumeric<Range, Output, Unknown> {
//...
}

but it really doesn't clear anything up for me.

I think I need to put some info inside the ScaleLinear brackets <> but I don't know what.

Any tips?

d3.js typescript
1 Answers

The first generic in ScaleLinear is Range, and the second is Output.

Range

The Range generic is for the type of the range data. If the range is specified in numbers (as in range([1, 10])) the range is of type number.

If the scale range is specified in strings such as colors (as in range(['red', 'blue'])), then the Range type is string.

Output

The Output generic is for the type of data that the scale outputs. If the scale interpolates numbers (as in range([1, 10])), the output is a number between 1 and 10, and so output is also of type number.

If the scale interpolates colors (as in range(['red', 'blue'])), the output is a color string (such as #9a3439), which is of type string.

For most cases, you can use ScaleLinear<number, number> for scales that interpolate numbers and ScaleLinear<string, string> for scales that interpolate color strings. In those cases where they are equal, you can also use the shorthand ScaleLinear<number> or ScaleLinear<string>.

user_149201880
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