Angular 1.x allowed to put elements in HTML, which were not known for W3C HTML Validator. Workaround for this was to add data- prefix and write e.g. data-ng-repeat instead of ng-repeat.
In the current Angular 2 version we have a different syntax. This syntax is also case-sensitive, e.g. we have to use ngClass, not ngclass.
All brackets used in Angular2 are causing HTML validation errors. Fortunately there is also a canonical form, so instead of (event) we can go with on-event, instead of [property] we can go with bind-property and instead of [(ngModel)] we can use bindon-ngModel. All those things work with data- prefix.
But what with directives like *ngFor, *ngIf and *ngSwitch? What with template variables #variable? Do you know any workaround in order to make Angular 2 template with those things a valid HTML in W3C Validator?
You have to use the canonical form. The * is for structural directives which can be used with the <template> tag. With * the template is implicit, but you can always use an explicit template tag instead and with this the canonical forms of the bindings you listed above.
See * and <template> in https://angular.io/docs/ts/latest/guide/template-syntax.html
来源：https://stackoverflow.com/questions/37480893/angular2-syntax-in-w3c-html-validator