Secure your apps with Angular Directive when using target='_blank'

#security #frontend #angular

Hi, today I want to share with you guys on how to secure your apps if you are using target='_blank'.

Usually to link an external url, we will do something like this:
<a href='https://dev.to'>Dev.to</a>.Please noted that this will still work. But unfortunately there is an security issues here.You can read more about it here and it also included with example:
https://mathiasbynens.github.io/rel-noopener/#hax

To solve this issue we can simply add an extra attribute to anchor tag.
<a href='https://dev.to' rel='noopener noreferrer'>Dev.to</a>.

However, let say in our app we have a lot of external link to put.
And personally, I dont really like to write rel='noopener noreferrer' to every anchor tag I have.

With that, we can automatically add rel='noopener noreferrer' to every anchor tag with Angular Directive.

// target-blank.directive.ts

import { Directive, HostBinding } from '@angular/core';

@Directive({
  // target every <a target="_blank">...<a>
  selector: 'a[target=_blank]',
})
export class TargetBlankDirective {
  // will add <a ... rel='noopener noreferrer'>...</a>
  @HostBinding('attr.rel') rel = 'noopener noreferrer';
}

// and just use it like this
<a href='someurl' target='_blank'>someurl</a>

// will render like this
<a href='someurl' target='_blank' rel='noopener noreferrer'>someurl</a>

One last thing, let say you have dynamic action on click. How would we want to prevent this.

function openInNewTab(url: string): void {
    // open link in new tab
    const newTab = window.open(url, '_blank')

    // set opener to null so that no one can references it
    newTab.opener = null
}

openInNewTab('https://dev.to')