Angular 12 - 不可分配给类型 '[number, number]

Question

I am trying out ngx-charts library in Angular 12 and I keep getting this issue:

Type 'any[]' is not assignable to type '[number, number]'.

Target requires 2 element(s) but source may have fewer.

I don't know what the error means.

Here is the code:

HTML:

<ngx-charts-linear-gauge 
  [view]="view" 
  [scheme]="colorScheme" 
  [value]="value" 
  [previousValue]="previousValue" 
  (select)="onSelect($event)" 
  [units]="units"
>
</ngx-charts-linear-gauge>

ts:

import { Component } from '@angular/core';

@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.scss']
})
export class AppComponent {

  single: any[];
  view: any[] = [400, 400];
  colorScheme = {
    domain: ['#aae3f5']
  };
  value: number = 43;
  previousValue: number = 70;
  units: string = 'counts';

  onSelect(event) {
    console.log(event);
  }

}

Any ideas on what the error means, how to fix this?

ts config code is:

{
  "compileOnSave": false,
  "compilerOptions": {
    "baseUrl": "./",
    "outDir": "./dist/out-tsc",
    "forceConsistentCasingInFileNames": true,
    "strict": false,
    "noImplicitReturns": true,
    "noFallthroughCasesInSwitch": true,
    "sourceMap": true,
    "declaration": false,
    "downlevelIteration": true,
    "experimentalDecorators": true,
    "moduleResolution": "node",
    "importHelpers": true,
    "target": "es2017",
    "module": "es2020",
    "lib": [
      "es2018",
      "dom"
    ]
  },
  "angularCompilerOptions": {
    "enableI18nLegacyMessageIdFormat": false,
    "strictInjectionParameters": true,
    "strictInputAccessModifiers": true,
    "strictTemplates": true
  }
}

Answer 1

I guess the issue is the type of you view property. According to the cods it must be of type number[] : doc-ref
note: the type in the docs is not exact enough. view is not defined as array of number ( number[] ), but as a tuple of 2 numbers ( [number, number] ) - source-code ref

But you define it as any[] .
Depending on your typescript compiler settings, you may get an error or warning.

When you need the exact correct type use:

// use as const so that typescript will infer the type [number, number] instead of number[]
view = [400, 400] as const;

The explict type would be:

view: [number, number] = [400, 400];

Answer 2

Set "strictTemplates": false in your tsconfig.json, like this:

 "angularCompilerOptions": {
   "enableI18nLegacyMessageIdFormat": false,
   "strictInjectionParameters": true,
   "strictInputAccessModifiers": true,
   "strictTemplates": false,
 }

Refs: Angular Compiler Options TypeScript Configuration