How to ignore text in input and output the entire list by clicking on the button?

I am using the widget jQuery UI for this.
By clicking on the button displays the whole list, but if something to enter, and then press again, it will come that introduced. How to ignore enter text and press to display the whole list?

Here is the JS code:
var city = ["Moskva", "Odintsovo", "Krasnodar", "vlasikha"];

 source: sity,
 minLength: 0,
 delay: 0

 $('#allViewSity').click(function(e) { 

Here is the html:
<input type="text" class="form-control" placeholder="Select a city" autocomplete="off" id="searchSity">
<a class="btn" id="allViewSity"><img src="img/down.png" alt></a>

June 3rd 19 at 20:20
1 answer
June 3rd 19 at 20:22
If you were to bother to read documentation, you would know that to ignore the content of the input is necessary when calling the method search to specify the desired value.

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