HTML

html value attribute

<!-- The value attribute is used to for example fill data to an input -->

<input type="text" value="I was already filled" id="textInput">

<!-- The value can be set or copied using JavaScrpit -->
<script>
	// Get your element
	var input = document.getElementById('textInput');
	
	// get the value
	var value = input.value;
	
	// set the value
	input.value = "i was changed";
</script>