angular - 延迟加载模块的类型提示

Question

在Angular中，我想延迟加载一些模块，例如amcharts。 我知道该怎么做，但是编辑器中的类型提示怎么样？

这是我的代码:

import {AfterViewInit, Component, NgZone, OnInit} from '@angular/core';
// import * as am4core from '@amcharts/amcharts4/core';
// import * as am4charts from '@amcharts/amcharts4/charts';
// import am4themes_animated from '@amcharts/amcharts4/themes/animated';

@Component({
  selector: 'app-wykres',
  templateUrl: './wykres.component.html',
})
export class WykresComponent implements OnInit, AfterViewInit {
  private am4core: any;
  private am4charts: any;
  private am4themesAnimated: any;
  chart: any;


  constructor(private zone: NgZone) {
  }

  ngOnInit() {
  }

  ngAfterViewInit() {
    this.zone.runOutsideAngular(() => {
      this.loadAmcharts()
        .then(() => {
          console.log('loaded', this.am4charts, this.am4themesAnimated, this.am4core);

          this.am4core.useTheme(this.am4themesAnimated);

          let chart = this.am4core.create('chartdiv', this.am4charts.XYChart);

          chart.paddingRight = 20;

          let data = [];
          let visits = 10;
          for (let i = 1; i < 366; i++) {
            visits += Math.round(
              (Math.random() < 0.5 ? 1 : -1) * Math.random() * 10
            );
            data.push({
              date: new Date(2018, 0, i),
              name: 'name' + i,
              value: visits
            });
          }

          chart.data = data;

          let dateAxis = chart.xAxes.push(new this.am4charts.DateAxis());
          dateAxis.renderer.grid.template.location = 0;

          let valueAxis = chart.yAxes.push(new this.am4charts.ValueAxis());
          valueAxis.tooltip.disabled = true;
          valueAxis.renderer.minWidth = 35;

          let series = chart.series.push(new this.am4charts.LineSeries());
          series.dataFields.dateX = 'date';
          series.dataFields.valueY = 'value';

          series.tooltipText = '{valueY.value}';
          chart.cursor = new this.am4charts.XYCursor();

          let scrollbarX = new this.am4charts.XYChartScrollbar();
          scrollbarX.series.push(series);
          chart.scrollbarX = scrollbarX;

          this.chart = chart;
        });
    });
  }

  private async loadAmcharts(): Promise<any> {
    this.am4core = await import('@amcharts/amcharts4/core');
    this.am4charts = await import('@amcharts/amcharts4/charts');
    this.am4themesAnimated = await import('@amcharts/amcharts4/themes/animated').then(resp => {
      return resp.default;
    });
  }
}

在 loadAmcharts 中，我正在加载模块并将它们分配给属性。但这些都是任何类型。

如果我评论:

import * as am4core from '@amcharts/amcharts4/core';
import * as am4charts from '@amcharts/amcharts4/charts';
import am4themes_animated from '@amcharts/amcharts4/themes/animated';

amchart 位于主包中。 我可以延迟加载模块并在编辑器中提供类型提示吗？

Answer 1

这是一个好问题。

这更多的是 TypeScript/IDE 问题，例如我找到了这个issue它描述了提示静态/动态导入之间的区别:

静态:

[...] .d.ts files are a static representation of what exists at runtime, and can be produced from TypeScript code or written manually for libraries that were not written in TS.

动态:

Not everything can just be inferred - capturing precise behavior would require literally running your program.

那么我们如何在编码时强制 TS 知道我们的类型是什么？ TypeScript 2.9 introduced a feature "import types" ，这仅适用于您的 IDE，以下是它在您的情况下的工作方式:

  private am4core: typeof import ('@amcharts/amcharts4/core');
  private am4charts: typeof import ('@amcharts/amcharts4/charts');
  private am4themesAnimated: typeof import ('@amcharts/amcharts4/themes/animated').default;

现在你应该得到代码提示:

    const core = this.am4core;
    const charts = this.am4charts;
    const animatedTheme = this.am4themesAnimated;

    console.log('loaded', core, charts, animatedTheme);

    core.useTheme(animatedTheme);

    const chart = core.create('chartdiv', charts.XYChart);

屏幕截图(我使用 VS Code):

希望这有帮助!