如何从下拉列表中选择值时禁用输入类型=“文本”[关闭]

I have a drop-down list) and one is input type="text". what i want if i select value{2,3} from drop down list not first value then input type will be disabled and if i select again first value then it will be enable.

Let's suppose you have this HTML code:

<select id='dropdown'>
  <option value="1">1</option>
  <option value="2">2</option>
  <option value="3">3</option>
</select>
<input type="text" id="textInput" />

Then you can act on change event on <select> to make <input> disabled or enabled by adding an event listener.

Since you're using jQuery (as you've added jquery tag to the question), the example code could look like this:

$('#dropdown').change(function() {
    if( $(this).val() == 1) {
        $('#textInput').prop( "disabled", false );
    } else {       
        $('#textInput').prop( "disabled", true );
    }
});

Here's a working fiddle: https://jsfiddle.net/wx38rz5L/2268/

You can hook into the select box's onchange event. If you set the first item to some known value (like an empty string, or "first" or whatever), you can check the current value and disable or enable the text box based on that.

var sel = document.getElementById("sel"), text = document.getElementById("text");

sel.onchange = function(e) {
  text.disabled = (sel.value !== "");
};

<select id="sel">
  <option value="">1</option>
  <option>2</option>
  <option>3</option>
</select>
<input type="text" id="text" />

</div>