doument.onkeyup code example
Example 1: html onkeyup set value
<input type="text" onkeyup="this.setAttribute('value', this.value);" value="">Example 2: javascript on keypu
<input type="text" onkeyup="myFunction()"><input type="text" onkeyup="this.setAttribute('value', this.value);" value=""><input type="text" onkeyup="myFunction()">