TypeScript编译器：@ types / d3-tip-无法调用类型缺少调用签名的表达式

Question

I am trying to understand this error, read all the questions with similar error message but couldn't find anything helping.

I am quite new to TypeScript, but getting there. I am trying to include the d3-tip module working with d3. I installed @types/d3 and @types/d3-tip. Now my code looks like this

import * as d3 from 'd3';
import * as d3Tip from 'd3-tip';
console.log(d3Tip) // => print the function signature from d3-tip module
console.log(d3Tip()) 
// => results in error 'Cannot invoke an expression whose type lacks a call signature'
d3.tip = d3Tip 
// => results in error 'Property 'tip' does not exist on type 'typeof "<my-project-path>/node_modules/@types/d3/index"''

I think I have two problems: first, I cannot call the d3-tip method, I don't really understand why if someone can explain that to me that'll be great.
Second, I cannot attach the d3Tip function as a new property of the d3 object (this is what I used to do with ES6, it worked great), then creating a tip with d3.tip() .

I know I can find other solutions, like designing the tip myself (it may have taken less time ^^), but I'd rather understand how to solve this.

Any ideas?

Answer 1

Good question. Initially I install with npm install @types/d3-tip . Then I need to copy ./node_modules/@types/d3-tip/index.d.ts to ./d3-tip.d.ts . Now the following code works:

import * as d3 from "d3";
import "./d3-tip";

d3.tip().hide();
let arc = d3.arc();

So the declarations in d3-tip.d.ts are merged into the d3 namespace as desired. Why it does not work without copying I have no clue. Any help?