The following code exhibits various examples related to getting/putting of values from input/select fields using JavaScript.
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Working Javascript & jQuery Demo


 <select id="Ultra" onchange="run()">  <!--Call run() function-->
     <option value="0">Select</option>
     <option value="8">text1</option>
     <option value="5">text2</option>
     <option value="4">text3</option>
</select><br><br>
TextBox1<br>
<input type="text" id="srt" placeholder="get value on option select"><br>
TextBox2<br>
<input type="text" id="rtt"  placeholder="Write Something !" onkeyup="up()">
The following script is getting the value of the selected option and putting it in text box 1
<script>
    function run() {
        document.getElementById("srt").value = document.getElementById("Ultra").value;
    }
</script>
The following script is getting a value from a text box 2 and alerting with its value
<script>
    function up() {
        //if (document.getElementById("srt").value != "") {
            var dop = document.getElementById("srt").value;
        //}
        alert(dop);
    }
</script>
The following script is calling a function from a function
<script>
    function up() {
        var dop = document.getElementById("srt").value;
        pop(dop); // Calling function pop
    }
    function pop(val) {
        alert(val);
    }?
</script>