Creating a custom visual for PowerBI in NodeJS - "Cannot find name 'IVisualHost' - node.js

Question

I'm trying to follow this tutorial on creating a custom visual for Power BI : https://learn.microsoft.com/en-us/power-bi/developer/custom-visual-develop-tutorial
The test with the default code works properly when I connect to Power BI Cloud, as shown in the part"Testing the custom visual" step 8, of the tutorial.
The problem is when I try to add the class-level properties in the visual.ts file (after I deleted the code as indicated in the part "Developing the visual elements" step 2 of the tutorial ), I get the error "Cannot find name 'IVisualHost'".
"use strict";
import "core-js/stable";
import "./../style/visual.less";
import powerbi from "powerbi-visuals-api";
import VisualConstructorOptions = powerbi.extensibility.visual.VisualConstructorOptions;
import VisualUpdateOptions = powerbi.extensibility.visual.VisualUpdateOptions;
import IVisual = powerbi.extensibility.visual.IVisual;
import EnumerateVisualObjectInstancesOptions = powerbi.EnumerateVisualObjectInstancesOptions;
import VisualObjectInstance = powerbi.VisualObjectInstance;
import DataView = powerbi.DataView;
import VisualObjectInstanceEnumerationObject = powerbi.VisualObjectInstanceEnumerationObject;
import { VisualSettings } from "./settings";
export class Visual implements IVisual {
private host: IVisualHost; ------------ the first error is here
private svg: d3.Selection<SVGElement>;
private container: d3.Selection<SVGElement>;
private circle: d3.Selection<SVGElement>;
private textValue: d3.Selection<SVGElement>;
private textLabel: d3.Selection<SVGElement>;
constructor(options: VisualConstructorOptions) {
this.svg = d3.select(options.element) ----------- the second error is here
.append('svg')
.classed('circleCard', true);
this.container = this.svg.append("g")
.classed('container', true);
this.circle = this.container.append("circle")
.classed('circle', true);
this.textValue = this.container.append("text")
.classed("textValue", true);
this.textLabel = this.container.append("text")
.classed("textLabel", true);
}
I also have this other error in the same visual.ts file : 'd3' refers to a UMD global, but the current file is a module. Consider adding an import instead. I imported the library with the commands : "npm i d3#3.5.5 --save" and "npm i #types/d3#3.5"
This is my pbiviz.json file :
{
"visual": {
"name": "visual9basic",
"displayName": "visual9basic",
"guid": "visual9basic252E75AF09794C8F8CE14414674FBC3E",
"visualClassName": "Visual",
"version": "1.0.0",
"description": "",
"supportUrl": "",
"gitHubUrl": ""
},
"apiVersion": "2.6.0",
"author": {
"name": "",
"email": ""
},
"assets": {
"icon": "assets/icon.png"
},
"externalJS": [
"node_modules/powerbi-visuals-utils-dataviewutils/lib/index.js",
"node_modules/d3/d3.min.js"
],
"style": "style/visual.less",
"capabilities": "capabilities.json",
"dependencies": null,
"stringResources": []
}
Here is my tsconfig.json :
{
"compilerOptions": {
"allowJs": false,
"emitDecoratorMetadata": true,
"experimentalDecorators": true,
"target": "es6",
"sourceMap": true,
"outDir": "./.tmp/build/",
"moduleResolution": "node",
"declaration": true,
"lib": [
"es2015",
"dom"
]
},
"files": [
"node_modules/powerbi-visuals-utils-dataviewutils/lib/index.js",
"./src/visual.ts",
"./src/settings.ts",
]
}

Answer 1

In Visual.ts, try adding the following import:
import IVisualHost = powerbi.extensibility.IVisualHost;
It should take care of the missing interface reference.
For the d3 reference you can try
import * as d3 from "d3";
Hope this helps. I haven't worked through the tutorial myself yet.

Answer 2

What I found out is that after a certain patch of npm, the ".api" folder isn't created any more. Instead, those files are stored under "node_modules/powerbi-visuals-api/". Also, the file "index.d.ts" replaces the former "PowerBI-visuals.d.ts".
But, I still have the 2 errors I described.