一个带有两个不同值的选项的文本框

Question

I have a form contain a textbox with tow option, one of the options is to write a just letter and the other option is to write a number, how can separate them?

when the user selected journal name it should write just a letter and when select ISSN it will enter a just number? function ValidateTextBox(txt) {

if (txt == "ISSN") {
    document.getElementById("searchword").pattern="[0-9]{4}[-]{1}[0-9]{3}[0-9Xx]{1}";
      document.getElementById("searchword").placeholder="like: 1111-1111 or 1111-111x";
}
 else {
      document.getElementById("searchword").pattern="[A-Za-z]{100}";
    document.getElementById("searchword").placeholder="International journal of Computers and Technology";

}

}

function inputLimiter(e,allow) { var AllowableCharacters = ''; if (allow == 'Letters'){AllowableCharacters=' ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz';} var k = document.all?parseInt(e.keyCode): parseInt(e.which); if (k!=13 && k!=8 && k!=0){ if ((e.ctrlKey==false) && (e.altKey==false)) { return (AllowableCharacters.indexOf(String.fromCharCode(k))!=-1); } else { return true; } } else { return true; } }

Answer 1

Check This http://jsfiddle.net/pjkhpxzx/ When A User Select A Value In Drop Down That Value Will Be Visible In The Text Box

This Done By A Simple JQuery

Below Is HTML

<select id="data">
    <option value=""></option>
<option value="text">text</option>
<option value="number">number</option>

below is Jquery

$(document).ready(function(e) {
$("#data").change(function(){
var item = $(this).val();        
  $("#dataval").attr("type",item)
});});