How can I conditionally disable the routerLink attribute?

Disable pointer-events on the element via CSS:

<a [routerlink]="xxx" [class.disabled]="disabled ? true : null">Link</a>

a.disabled {
   pointer-events: none;
   cursor: default;
}

See also Angular2, what is the correct way to disable an anchor element?

or

<a *ngIf="isEnabled" [routerlink]="xxx">Link</a>
<div *ngIf="!isEnabled">not a link</div>

or to easily reuse the disabled link template

<ng-template #disabledLink>
  <div *ngIf="!isEnabled">not a link</div>
</ng-template>
<a *ngIf="isEnabled; else disabledLink" [routerLink]="xxx">Link</a>

Angular 13 and above

[routerLink]="null" (and undefined) is now officially used to disable the routerLink.
(see Docs)

So this is enough:

<a [routerLink]="linkEnabled ? 'path' : null">Link</a>

Angular 12 and below

[routerLink]="null" (and undefined) is treated as a shorthand for an empty array of commands. So it makes the routerLink to link to the current/active route. This behavior allows us to abuse the routerLinkActive directive for our purpose:

Template:

<a [routerLink]="linkEnabled ? 'path' : null"
   [routerLinkActive]="linkEnabled ? 'is_active' : 'is_disabled'">Link</a>

Optional CSS:

.is_disabled {
    cursor: default;
    text-decoration: none;
}

.is_active {
    // your style for active router link
}

Live demo (Angular 10):
See demo on StackBlitz

Detailed Description:

When linkEnabled returns false, null will make routerLink to link to the current/active route.

If routerLink links to the active route, the class which is specified in routerLinkActive will be applied. That will be is_disabled in this case.

There we can specify, how the disabled routerLink should appear.

routerLink to the active route won't trigger a navigation event.

I've just had some success with a similar issue: having an array of nav links in an ngFor, some required [routerLink], while others required (click) - my issue was that all links relied on [routerLink] for [routerLinkActive], so I had to stop routerLink, without touching it's value.

`<a [routerLink]="item.link" routerLinkActive="isActive">
    <span (click)="item.click ? item.click($event) : void>
</a>`

with:

`click: ($event) => {
    $event.stopPropagation(); // Only seems to
    $event.preventDefault(); // work with both
    // Custom onClick logic
}`

As the span is inside, you can be sure the cancelling of the event happens before it bubbles up to [routerLink], while routerLinkActive will still apply.

Disabling pointer-events on any html tag:

<div [routerLink]="['/home', { foo: bar }]"
     [ngStyle]="{'pointer-events': myLinkEnabled ? 'none' : null}">
     Click me
</div>

'none' resolves to disabling pointer-events, that is, disabling the link.

null resolves to ignore the style.