javascript-textfield: How to set the value in a textfield by javascript?

setAttribute("attribute-name","value") sets the value but not visible in textfield. to set the value in textfield just get the textfield element by javascript and assign the value in it as follows:

<script type="text/javascript">
function set(a){
document.getElementById("set").value=a;
document.getElementById("set").setAttribute("value",a);
}
</script>
<input type="text" id="set" name="set"/>
<input type="button" onclick="set(this.value)" value="Say Hello" />

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