发表新帖
发表新帖

Getting value of select (dropdown) before change

后端 未结
关注
18 2459
无人共我
无人共我 2020-11-22 08:56

The thing I want to achieve is whenever the

提交评论
  •  加载中...
  • 悲哀的现实
    2020-11-22 08:58

    There are several ways to achieve your desired result, this my humble way of doing it:

    Let the element hold its previous value, so add an attribute 'previousValue'.

    <select id="mySelect" previousValue=""></select>

    Once initialized, 'previousValue' could now be used as an attribute. In JS, to access the previousValue of this select:

    $("#mySelect").change(function() {console.log($(this).attr('previousValue'));.....; $(this).attr('previousValue', this.value);}

    After you are done using 'previousValue', update the attribute to current value.

    0 讨论(0)
  • 陌清茗
    2020-11-22 08:58

    I needed to reveal a different div based on the selection

    This is how you can do it with jquery and es6 syntax

    HTML

    <select class="reveal">
    <option disabled selected value>Select option</option>
    <option value="value1" data-target="#target-1" >Option 1</option>
    <option value="value2" data-target="#target-2" >Option 2</option>
</select>
<div id="target-1" style="display: none">
    option 1
</div>
<div id="target-2" style="display: none">
    option 2
</div>

    JS

    $('select.reveal').each((i, element)=>{
    //create reference variable 
    let $option = $('option:selected', element)
    $(element).on('change', event => {
        //get the current select element
        let selector = event.currentTarget
        //hide previously selected target
        if(typeof $option.data('target') !== 'undefined'){
            $($option.data('target')).hide()
        }
        //set new target id
        $option = $('option:selected', selector)
        //show new target
        if(typeof $option.data('target') !== 'undefined'){
            $($option.data('target')).show()
        }
    })
})
    0 讨论(0)
  • 情书的邮戳
    2020-11-22 08:59

    Track the value by hand.

    var selects = jQuery("select.track_me");

selects.each(function (i, element) {
  var select = jQuery(element);
  var previousValue = select.val();
  select.bind("change", function () {
    var currentValue = select.val();

    // Use currentValue and previousValue
    // ...

    previousValue = currentValue;
  });
});
    0 讨论(0)
  • 醉梦人生
    2020-11-22 08:59

    keep the currently selected drop down value with chosen jquery in a global variable before writing the drop down 'on change' action function. If you want to set previous value in the function you can use the global variable.

    //global variable
var previousValue=$("#dropDownList").val();
$("#dropDownList").change(function () {
BootstrapDialog.confirm(' Are you sure you want to continue?',
  function (result) {
  if (result) {
     return true;
  } else {
      $("#dropDownList").val(previousValue).trigger('chosen:updated');  
     return false;
         }
  });
});
    0 讨论(0)
  • 执笔经年
    2020-11-22 09:05

    please don't use a global var for this - store the prev value at the data here is an example: http://jsbin.com/uqupu3/2/edit

    the code for ref:

    $(document).ready(function(){
  var sel = $("#sel");
  sel.data("prev",sel.val());

  sel.change(function(data){
     var jqThis = $(this);
     alert(jqThis.data("prev"));
     jqThis.data("prev",jqThis.val());
  });
});

    just saw that you have many selects on page - this approach will also work for you since for each select you will store the prev value on the data of the select

    0 讨论(0)
    • 1 2 3 下一页
     看不清?
    提交回复
    热议问题