NG2 - selectAllNotSelected-Checkbox

thanx - for Ref:
http://stackoverflow.com/questions/34219199/angular2-how-to-get-all-selected-check-boxes

.html
--------

<button value="all" (click)="bulk('all')">ALL</button>
<button value="none" (click)="bulk('none')">NONE</button>

<div *ngFor="#students of student_list #i=index">
  <input type="checkbox" value={{students.id}} class="checkedStudent"
  (change)="checkedStudents(students.id)" id={{students.id}}>
</div>

.ts
-----

abc:Array<any>= [];
checkedStudents(value) {
        console.log(value);
        if ((<HTMLInputElement>document.getElementById(value)).checked === true) {
            this.abc.push(value);
        }
        else if ((<HTMLInputElement>document.getElementById(value)).checked === false) {
            let indexx = this.abc.indexOf(value);
            this.abc.splice(indexx,1)
        }
        console.log(this.abc)
    }

// for Bulk actions

bulk(a) {
        // console.log(a);
        if (a == "all") {
            console.log("yes all");
            this.abc = [];
            for (let i = 0; i < this.student_list.length; i++) {
                (<HTMLInputElement>document.getElementsByClassName("checkedStudent")[i]).checked = true;
                this.abc.push(this.student_list[i].id);
            }
        }
        if (a == "none") {
            for (let i = 0; i < this.student_list.length; i++) {
                (<HTMLInputElement>document.getElementsByClassName("checkedStudent")[i]).checked = false;
            }
            this.abc = [];
        }
        console.log(this.abc);
    }