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

@Directive({
    selector: '[appServerSuccess]'
})

export class ServerSuccessDirective implements OnInit {
    @Input() appServerSuccess: string;
    @HostBinding()
    get innerText() {
       return this.appServerSuccess;
    }
    @HostBinding('class.success')
    get success () {
       return this.appServerSuccess.toLocaleLowerCase().includes('success');
    }

    constructor() {}
    ngOnInit() {}
}

import { NgModule } from "@angular/core";
import { ServerSuccessDirective } from './directives/server-success.directive';


@NgModule({
    imports: [ ],
    declarations: [ ServerSuccessDirective ],
    exports: [ ServerSuccessDirective ]
})

export class SharedModule {}

<div [appServerSuccess]="msg"></div>