Detailed explanation of Angular's implementation of form validation function-JS Tutorial-php.cn

Angular form validation is divided into two types of validation: 1. Built-in validation (required, minlength, etc.); 2. Custom validation (regular expression). This article mainly introduces the form verification function of Angular in detail. It has certain reference value. Interested friends can refer to it. I hope it can help you.

Next, let’s use a demo to register an account to see how these two verifications are implemented.

Project interface

1. Built-in verification

Among the accounts There are required verification and minimum length verification, and the other two are only required verification

1. Project directory

----------app.component.ts

----------app.component.html

----------app.component.css

------ ----app.module.ts

2. Project code

app.module.ts

import { BrowserModule } from '@angular/platform-browser'; import { NgModule } from '@angular/core'; import { FormsModule,ReactiveFormsModule } from '@angular/forms';//表单验证必须导入这两个模块 import { AppComponent } from './app.component'; @NgModule({ declarations: [ AppComponent ], imports: [ BrowserModule, FormsModule, //注册模块 ReactiveFormsModule ], providers: [], bootstrap: [AppComponent] }) export class AppModule { }

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app.component. ts

import { Component,OnInit } from '@angular/core'; import { FormGroup, FormControl, Validators } from '@angular/forms'; @Component({ selector: 'app-root', templateUrl: './app.component.html', styleUrls: ['./app.component.css'] }) export class AppComponent { title = 'app'; Form:FormGroup; data={ name:"", email:"", tel:"" } ngOnInit(): void { this.Form = new FormGroup({ 'name': new FormControl(this.data.name, [ Validators.required, Validators.minLength(4) ]), 'email': new FormControl(this.data.email, Validators.required), 'tel': new FormControl(this.data.tel, Validators.required) }); } get name() { return this.Form.get('name'); } get email() { return this.Form.get('email'); } get tel() { return this.Form.get('tel'); } }

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Simply speaking, when using the verification form, it is roughly divided into four steps:

(1) Import related modules FormGroup, FormControl, Validators;

(2) Declare the form validation variable From:FromGroup;

(3) Define validation rules;

(4) Through the control group (FormGroup) to which it belongs The get method to access the form control

app.component.html

注册账号

账户名：

请输入长度账户名！

账户名长度不小于4！

邮箱：

请输入邮箱！

电话:

请输入电话！

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app.component.css

*{ font-size: 18px; } .wrapper{ margin: 0 auto; margin-top:10%; width:30%; height: 20%; border:1px solid black; border-radius: 10px; } .title-wrapper{ margin: 0 auto; padding-top: 20px; padding-bottom: 20px; width:370px; text-align: center; font-size: 20px; font-weight: 800; } label{ display: inline-block; width:72px; } .contain-wrapper{ width: 300px; margin:0 auto; } .confirm{ margin-top:20px; width:100%; }

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3. Project effect

2. Custom verification

Custom form verification, required Create a custom validator. Next, we change the verification of the mailbox to formatted verification instead of simple existence verification. First, let’s take a look at the changes to the project directory

1.Project Directory

----------app.component.ts

----------app.component.html

--- -------app.component.css

----------app.module.ts

----------emailAuthentication .ts

2. Project code

app.module.ts

import { BrowserModule } from '@angular/platform-browser'; import { NgModule } from '@angular/core'; import { FormsModule,ReactiveFormsModule } from '@angular/forms'; import { EmailValidatorDirective } from './emailAuthentication'; import { AppComponent } from './app.component'; @NgModule({ declarations: [ AppComponent, EmailValidatorDirective ], imports: [ BrowserModule, FormsModule, ReactiveFormsModule ], providers: [], bootstrap: [AppComponent] }) export class AppModule { }

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emailAuthentication.ts

import { Directive, Input, OnChanges, SimpleChanges } from '@angular/core'; import { AbstractControl, NG_VALIDATORS, Validator, ValidatorFn, Validators } from '@angular/forms'; /** A hero's name can't match the given regular expression */ export function emailValidator(nameRe: RegExp): ValidatorFn { return (control: AbstractControl): { [key: string]: any } => { const forbidden = !nameRe.test(control.value); return forbidden ? { 'forbiddenName': { value: control.value } } : null; }; } @Directive({ selector: '[appForbiddenName]', providers: [{ provide: NG_VALIDATORS, useExisting: EmailValidatorDirective, multi: true }] }) export class EmailValidatorDirective implements Validator { @Input() forbiddenName: string; validate(control: AbstractControl): { [key: string]: any } { return this.forbiddenName ? emailValidator(new RegExp(this.forbiddenName, 'i'))(control) : null; } }

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app.component.ts

import { Component,OnInit } from '@angular/core'; import { FormGroup, FormControl, Validators } from '@angular/forms'; import { emailValidator } from './emailAuthentication'; //导入emailValidator自定义验证器 @Component({ selector: 'app-root', templateUrl: './app.component.html', styleUrls: ['./app.component.css'] }) export class AppComponent { title = 'app'; //email的正则表达式 emailExp = /^([a-zA-Z0-9_-])+@([a-zA-Z0-9_-])+(.[a-zA-Z0-9_-])+/ ; Form:FormGroup; data={ name:"", email:"", tel:"" } ngOnInit(): void { this.Form = new FormGroup({ 'name': new FormControl(this.data.name, [ Validators.required, Validators.minLength(4) ]), 'email': new FormControl(this.data.email, [ Validators.required, emailValidator(this.emailExp) //自定义验证器 ]), 'tel': new FormControl(this.data.tel, Validators.required) }); } get name() { return this.Form.get('name'); } get email() { return this.Form.get('email'); } get tel() { return this.Form.get('tel'); } }

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app.component.html

注册账号

账户名：

请输入账户名！

账户名长度不小于4！

邮箱：

请输入正确格式的邮箱！

电话:

请输入电话！

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In the final confirmation, we set the disabled attribute of the button. When the form verification fails, the confirmation button cannot be clicked and displays an unclickable state. [disabled]="Form.invalid".

3. Project effect

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JQuery form validation example code

Implementing form validation in JavaScript

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