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In this short tutorial, You will learn about how to do url validation in Angular and typescript application with input form.
This tutorials works all angular versions 2,5,6 8,9,10,11 versions
Other versions available:
- VueJS Input type url validation
- ReactJS Input type url validation Url pattern validation can be implement with multiple approaches
URL pattern validation example with reactive forms
First, in application html template component created to display the input form and do the following steps
- Define the form element with
FormGroup directivewith urlForm binding - Inside form, define input element with
formControlNamename url - validation errors are bound and available with
urlForm.controls[url] - Validation check added for input box is not empty(errors.required) and focus is in it(touched)
- if binded errors contains required, displayed error message ‘URL is required’
- if errors contains pattern, display error message ‘URL format is wrong’
<div>
<h2>{{ heading | titlecase }}</h2>
<form [formGroup]="urlForm">
<input type="text" formControlName="url" />
<div *ngIf="!urlForm.controls['url'].valid && urlForm.controls['url'].touched">
<div *ngIf="urlForm.controls['url'].errors.required" style="background-color: red">
URL is required
</div>
<div *ngIf="urlForm.controls['url'].errors.pattern" style="background-color: red">
URL format is wrong
</div>
</div>
</form>
<button type="submit ">Submit</button>
</div>
Next, In application controller component, define the logic for regex pattern validation
- Declared urlForm of type
FormGroupwhich already has an binding to form element. - Defined the
url regular expression patterninto variable - In the constructor, initialized urlForm with new FormControl element ie url
- these url form control will be bind with input element in html template
Validators.requiredadded for not empty validation checkValidators.patternadded for url regular expression- These validations are checked with
blurevent `updateOn: blur’ property
import { Component } from '@angular/core';
import { FormControl, FormGroup, Validators } from '@angular/forms';
@Component({
selector: 'app-root',
templateUrl: './app.component.html',
styleUrls: ['./app.component.scss'],
})
export class AppComponent {
heading = 'angular url pattern validation with examples';
urlForm: FormGroup;
myusername: string = '';
urlRegEx =
'[-a-zA-Z0-9@:%_+.~#?&//=]{2,256}(.[a-z]{2,4})?\b(/[-a-zA-Z0-9@:%_+.~#?&//=]*)?';
constructor() {
this.urlForm = new FormGroup({
url: new FormControl('', {
validators: [Validators.required, Validators.pattern(this.urlRegEx)],
updateOn: 'blur',
}),
});
}
submit() {
console.log(this.urlForm.value);
}
}
And output you seen in browser is
Angular html5 input type url pattern validation
In modern browsers, Easy approach is to do url pattern validation with inbuilt html5 language
Another way to do url validation is to define the input type=url in html element. However this only supports html5 only and modern browsers.
Input is defined with following attributes
<input type="url" name="websiteurl" id="websiteurl" placeholder="https://example.com" [(ngModel)]="websiteurl" [ngModelOptions]="{ updateOn: 'blur' }" #urlerror="ngModel" pattern="[-a-zA-Z0-9@:%_+.~#?&//=]{2,256}(.[a-z]{2,4})?\b(/[-a-zA-Z0-9@:%_+.~#?&//=]*)? "
type=url is an input textbox, accepts urls only pattern attribute value is regular expression pattern for url values NgModel directive is to support two way binding from view to controller and viceversa ngModelOptions directive enables to change the behaviour of ngModel value, this will be fired with updateon:blur event.
Following is an complete code
<div>
<input type="url" name="websiteurl" id="websiteurl" placeholder="https://example.com" [(ngModel)]="websiteurl" [ngModelOptions]="{ updateOn: 'blur' }" #urlerror="ngModel" pattern="[-a-zA-Z0-9@:%_+.~#?&//=]{2,256}(.[a-z]{2,4})?\b(/[-a-zA-Z0-9@:%_+.~#?&//=]*)? "
required />
<div *ngIf="urlerror.invalid && (urlerror.dirty || urlerror.touched)">
<div *ngIf="urlerror.errors.required">
<span style="background-color: red">URL is required </span>
</div>
<div *ngIf="urlerror.errors.pattern">
<span style="background-color: red">Invalid URL </span>
</div>
</div>
</div>
In the component, just declare input elements name here with default value
import { Component } from '@angular/core';
import { FormControl, FormGroup, Validators } from '@angular/forms';
@Component({
selector: 'app-root',
templateUrl: './app.component.html',
styleUrls: ['./app.component.scss'],
})
export class AppComponent {
heading = 'angular html5 URL pattern validation example';
websiteurl: string = '';
}
Typescript url regexp validation
Sometimes, We want to do validation typescript file.
- It uses same above regular expression pattern for url validation
- RegExp object is created with regex
pattern.testchecked against supplied url and return true-valid
public isValidUrl(urlString: string): boolean {
try {
let pattern = new RegExp(this.urlRegEx);
let valid = pattern.test(urlString);
return valid;
} catch (TypeError) {
return false;
}
}
}
}
console.log(this.isValidUrl('https://www.google.com')); // true
console.log(this.isValidUrl('google')); // false
Conclusion
On this post, You learned
- Angular url pattern validation example with reactive forms
- HTML 5 input type url form validation
- Typescript url validation