如何在角分量中使用debounceTime？

Question

我在寻找一个解决方案，与反应形式的工作

Answer 1

实现这一功能的方法（或至少是一种）是动态地删除和添加验证器。

在输入中，使用keydown绑定，当用户开始键入时，它将删除验证器；使用keyup绑定，它将通过debounceTime管道运行，然后重新应用验证器（但仅在指定的debounceTime时间过后）。

此处代码：

import { Component, OnInit } from '@angular/core';
import { FormBuilder, FormGroup, Validators } from '@angular/forms';
import { Subject } from 'rxjs';
import { debounceTime } from 'rxjs/operators';

@Component({
    selector: 'form-component',
    template: `
        <form [formGroup]="formGroup">
          <input type="text" formControlName="name" (keyup)="onKeyUp()" (keydown)="onKeyDown()" [ngClass]="{ 'invalid': formGroup.controls.name.invalid }">
        </form>
      `,
    styles: [
        '.invalid { border-color: red; color: red; }'
    ]
})
export class FormComponent implements OnInit {

    formGroup: FormGroup;
    subject: Subject<any> = new Subject();

    constructor(private formBuilder: FormBuilder) {}

    ngOnInit(): void {
        this.formGroup = this.formBuilder.group({
            name: [ '' ]
        });

        // Subscribe to the subject, which is triggered with each keyup
        // When the debounce time has passed, we add a validator and update the form control to check validity
        this.subject
            .pipe(debounceTime(500))
            .subscribe(() => {
                    this.formGroup.controls.name.setValidators([ Validators.minLength(5) ]);
                    this.formGroup.controls.name.updateValueAndValidity();
                }
            );
    }

    onKeyUp(): void {
        this.subject.next();
    }

    onKeyDown(): void {
        // When the user starts to type, remove the validator
        this.formGroup.controls.name.clearValidators();
    }

}