wijmo.angular2.input is an external TypeScript module that can be imported to your code using its ambient module name. For example:

import * as wjInput from 'wijmo/wijmo.angular2.input';
 
@Component({
    directives: [wjInput.WjInputNumber],
    template: '<wj-input-number [(value)]="amount"></wj-input-number>',
    selector: 'my-cmp',
})
export class MyCmp {
    amount = 0;
}