PHP

https://stackoverflow.com/questions/58589741/angular-8-hide-divs-and-show-div-on-button-click

<div *ngIf="div1">
    ABC
</div>
<div>
    DEF
</div>
<div>
    GHI
</div>
<button (click)="div1Function()"></button>
<button (click)="div2Function()"></button>
<button (click)="div3Function()"></button>

https://stackoverflow.com/questions/58589741/angular-8-hide-divs-and-show-div-on-button-click

    div1:boolean=true;
    div2:boolean=true;
    div3:boolean=true;

    div1Function(){
        this.div1=true;
        this.div2=false;
        this.div3=false
    }

    div2Function(){
        this.div2=true;
        this.div1=false;
        this.div3=false
    }

    div3Function(){
        this.div3=true;
        this.div2=false;
        this.div1=false
    }

https://stackoverflow.com/questions/58589741/angular-8-hide-divs-and-show-div-on-button-click

$url = "http://localhost/main.php?email=$email_address&event_id=$event_id";
//                               ^ start of vars      ^next var