how to set value in input by JavaScript?

Question

I have input field with id txt1 but I am unable to change the value from JavaScript.

<form action=""> 
First name: <input type="text" id="txt1" onkeyup="showHint(this.value)">
</form>

<script>
  document.getElementById('txt1').value('anyvalue1111');
</script>

Note: I find on stackoverflow how to change input value but could not found any answer. Title of the question save lot of time. It is valid question in this way.

Answer 1

value is a property and not a method.

document.getElementById('txt1').value = 'anyvalue1111';

Answer 2

Try this

<form action=""> 
    First name: <input type="text" id="txt1" onkeyup="showHint(this.value)">
    </form>

    <script>
    document.getElementById('txt1').value = 'Hello world!!';

    </script>