OnChange Typescript input - html

Question

I want to be able to trigger an on change when a file is selected from a input(file). I want the triggered event to set a textbox to be the name of the file.
I am using HTML5, Typescript and Angular2. I can't figure out or find an example of exactly how to produce the behavior I am after.
see my code below:
component.ts
import { Component } from '#angular/core';
import { Http } from '#angular/http';
import { Headers, RequestOptions } from '#angular/http';
#Component({
selector: 'testConnection',
// ignore error on require
template: require('./testConnection.component.html')
})
export class TestConnectionComponent {
public http: Http;
public requestData: RequestData;
public constructor(http: Http) {
this.http = http;
(<HTMLInputElement>document.getElementById('fileInput')).onchange = (ev: Event) => {
var fileInput = (<HTMLInputElement>ev.srcElement).files[0];
var fileTextbox = (<HTMLInputElement>document.getElementById('fileTextbox'));
fileTextbox.value = fileInput.name;
}
}
public testButtonClick() {
// Iniatialise Request object
let request: RequestData;
request = { "CountryCode": "", "SiteIDList": "" };
// Get site(s)
var siteIdList = (<HTMLInputElement>document.getElementById('siteIDInput')).value;
// Get selected country
var countryCode = (<HTMLInputElement>document.getElementById('countryDropdown')).value;
// Veryify contents is just site ids.
// TODO
request.CountryCode = countryCode;
request.SiteIDList = siteIdList;
// Set Http POST options
let headers = new Headers({ 'Content-Type': 'application/json' });
let options = new RequestOptions({ headers: headers });
// Call Api with test connection data
this.http
.post('/api/TestConnection/TestConnection', JSON.stringify(request), options)
.subscribe(data => {
// alert request ok
alert('ok');
}, error => {
// Log error
console.log(error.json());
});
}
}
interface RequestData {
SiteIDList: string;
CountryCode: string;
}
component.html
<h2>Test Site Connection</h2>
<p>This will allow you to check the connectivity of a set of sites by either individually or uploading a CSV file of Site IDs.</p>
<br />
<div class="panel panel-primary">
<div class="panel-heading">
<h3 class="panel-title">Manual Test</h3>
</div>
<div class="panel-body">
<p>
Select the country and the sites you want to test.
</p>
<ul>
<li>Multiple sites can be selected using commas (,).</li>
<li>you can see results in the Site Connection Results tab</li>
</ul>
<br />
<!--Replace with lookup to enabled countries-->
<div class="form-group col-lg-4">
<div class="col-lg-6">
<select class="form-control" id="countryDropdown">
<option>Select Country</option>
<option>US</option>
<option>SG</option>
<option>NL</option>
</select>
</div>
</div>
<div>
<div class="col-lg-4">
<input type="text" class="form-control" placeholder="SiteID(s)" id="siteIDInput" />
</div>
<button class="btn btn-primary" (click)="testButtonClick()">Test</button>
</div>
</div>
</div>
<div class="panel panel-success">
<div class="panel-heading">
<h3 class="panel-title">Upload file</h3>
</div>
<div class="panel-body">
<div>
<p>Upload a CSV file of sites to test all at once.</p>
<br />
<div class="col-lg-4">
<input type="text" class="col-lg-4 form-control" id="fileTextbox" disabled/>
</div>
<label class="btn btn-primary">
Browse <input type="file" id="fileInput" style="display:none;" onchange="{ setFileName() }"/>
</label>
<button class="btn btn-primary" (click)="searchButtonClick()">Test</button>
</div>
</div>
</div>
<div class="modal">
<div class="modal-dialog">
<div class="modal-content">
<div class="modal-header">
<button type="button" class="close" data-dismiss="modal" aria-hidden="true">×</button>
<h4 class="modal-title">Modal title</h4>
</div>
<div class="modal-body">
<p>One fine body…</p>
</div>
<div class="modal-footer">
<button type="button" class="btn btn-default" data-dismiss="modal">Close</button>
<button type="button" class="btn btn-primary">Save changes</button>
</div>
</div>
</div>
</div>

Answer 1

Try using (change) event binding
<input type="file" id="fileInput" style="display:none;" (change)="setFileName()"/>

Answer 2

If you need to retrieve the file name before uploading it you can do it this way :
#Component({
selector: 'my-app',
template: `
<div>
<input type="file" (change)="onChange($event)"/>
</div>
<p>Filename : {{filename}}</p>
`,
providers: []
})
export class AppComponent {
filename: string;
constructor() { }
onChange(event) {
this.filename = event.srcElement.files[0].name;
}
}
Here is a working plunker