angular

Question

我正在构建一个 angular 库（我们将其视为“mylib”）。在这个库中，我只使用了 mylib.component.ts 文件。我在这个文件的模板变量中添加了 html 元素代码。用于修改那些 html 元素的函数也在同一个 component.ts 文件中。我成功构建了它并发布到 npm。但是当我尝试在新项目中安装和使用它时，它说这些功能不存在。我做错了什么？我只想知道如何访问 angular 库的 component.ts 中声明的函数。如果不行，那么在另一个项目中安装这个库后，我应该如何访问这些功能？

mylib.component.ts

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

@Component({
  selector: 'srr-mylib',
  template: `
    <h1> Random Text </h1>
  `,
  styles: [
  ]
})
export class ElapsedtimerComponent implements OnInit {

 
  constructor() { }

  ngOnInit(): void {
  }

  startTrans(){

    //some code here

  }
}

mylib.module.ts

import { NgModule } from '@angular/core';
import { MylibComponent } from './mylib.component';
import { CommonModule } from '@angular/common';  
import { BrowserModule } from '@angular/platform-browser';



@NgModule({
  declarations: [MylibComponent],
  imports: [
    CommonModule,
    BrowserModule
  ],
  exports: [MylibComponent]
})
export class MylibModule { }

public.api.ts

/*
 * Public API Surface of mylib
 */

export * from './lib/mylib.service';
export * from './lib/mylib.component';
export * from './lib/mylib.module';

这就是我尝试在新项目中使用上述库的方式

app.component.html

<srr-mylib></srr-mylib>

app.component.ts

import { Component } from '@angular/core';
import { MylibModule } from '@somename/mylib'

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

  constructor(
    private libz:MylibModule
  ) {
 
  libz.startTrans()  //<----- this doesn't work. it gives the error as "Property 'startTrans' does not exist on type 'MylibModule'.ts(2339)"
  }
 

}

app.module.ts

import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';

import { AppComponent } from './app.component';
import { MylibModule } from '@somename/mylib'

@NgModule({
  declarations: [
    AppComponent
  ],
  imports: [
    BrowserModule,
    MylibModule
  ],
  providers: [],
  bootstrap: [AppComponent]
})
export class AppModule { }

Answer 1

在Angular中，一个组件不应该直接调用另一个组件的方法。因此，根据我对您尝试执行的操作的了解，我会改用 @Input，它会触发函数调用：

mylib.component.ts

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

@Component({
  selector: 'srr-mylib',
  template: `
    <h1 [ngStyle]="{'font-size': myFontSize}"> Random Text </h1>
    <button type="button" (click)="onClickPlusFontSize()">Larger font size</button>
  `,
  styles: [
  ]
})
export class ElapsedtimerComponent implements OnInit, OnChanges {

  @Input() inputFontSize: number;
  @Output() inputFontSizeChange: EventEmitter<number> = EventEmitter();

  public myFontSize: string;

  constructor() {
  }

  ngOnInit(): void {
  }


  ngOnChanges(changes: SimpleChanges): void {
    if (changes.inputFontSize) {
      // triggered every time the @Input value changes
      this.onFontSizeChange(changes.inputFontSize.currentValue);
    }
  }

  onFontSizeChange(newFontSize) {
    this.myFontSize = `${newFontSize}px`;
    // some other stuff
  }

  onClickPlusFontSize() {
    this.inputFontSize++; // updates the value
    onFontSizeChange(this.inputFontSize); // triggers the function that should be called, as if the change came from the parent
    this.inputFontSizeChange.emit(this.inputFontSize) // tells the parent that the value changed
  }
}

app.component.html

<srr-mylib [(inputFontSize)]="myLibFontSize" (inputFontSizeChange)="onFontSizeChange($event)"></srr-mylib>

app.component.ts

import { Component } from '@angular/core';
import { MylibModule } from '@somename/mylib'

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

  constructor() {
    this.myLibFontSize = 12; // will trigger ngOnChanges on myLib
  }

  onSpecificEvent() {
    // do stuff
    this.myLibFontSize = 20; // will also trigger ngOnChanges on myLib
  }
 
  onFontSizeChange(newFontSize: number) {
    // this method is optionnal.
    // with '[(inputFontSize)]="myLibFontSize"' in the HTML, the value of 'myLibFontSize' will already be updated automatically.
    // this function is only useful if the parent wants to do specific work when the value changes.
    // so there is absolutely no need to do "this.myLibFontSize = newFontSize" here.
    // the only thing to know, is that you have no clue of either 'myLibFontSize' will be updated after of before 'onFontSizeChange' is called.
    // So always use 'newFontSize' in this method, to be sure of the value used.
    console.log('myLibFontSize value changed !', newFontSize);
  }

}

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