Question

I am trying to get the value from a drop down list in JavaScript and HTML which are two dates ( the format is just year), but I have an error of say " TypeError: "#sortDateFrom".val is not a function "

I want to check if the beginning is smaller then the end.

MY HTML code:

<div class="col-lg-2 col-md-2 col-sm-2">
    <select class="form-control" id="sortDateFrom">
        <option selected disabled>-Date From-</option>
        <option>1900</option>
        <option>1910</option>
        <option>1920</option>
        <option>1930</option>
        <option>1940</option>
        <option>1950</option>
        <option>1960</option>
        <option>1970</option>
        <option>1980</option>
        <option>1990</option>
        <option>2000</option>
        <option>2010</option>
    </select>
</div> <!-- end column 3: Date From -->
<div class="col-lg-2 col-md-2 col-sm-2">
    <select class="form-control" id="sortDateTo">
        <option selected disabled>-Date To-</option>
        <option>1900</option>
        <option>1910</option>
        <option>1920</option>
        <option>1930</option>
        <option>1940</option>
        <option>1950</option>
        <option>1960</option>
        <option>1970</option>
        <option>1980</option>
        <option>1990</option>
        <option>2000</option>
        <option>2010</option>
    </select>
</div> <!-- end column 3: Date To -->

And my Function in Javascript:

<script>    
    $(document).ready(function(){       
        var startDate = ('#sortDateFrom').val();
        var endDate = ('#sortDateTo').val();

        if (startDate < endDate){
            window.alert("The beginning date must be smaller then the end date ");
        }       
    });     
</script>

Answer 1

你忘记了jquery $

您还需要在页面准备就绪时检查值何时更改

<script>    
    $(document).ready(function(){       
        var startDate = $('#sortDateFrom').val();
        var endDate = $('#sortDateTo').val();
        $('#sortDateFrom, #sortDateTo').change(function(){
            if (startDate < endDate){
            window.alert("The beginning date must be smaller then the end date ");
        })
        }
    });
    //
</script>

Answer 2

看看这个：

您未在DEBUG=express:application node .

中传递 $

必须通过选项：选择。请注意你不要在选项中使用价值。为此，您使用.text（）而不是.val（）。

＆＃13;

$('#sortDateFrom option:selected').text()

＆＃13;

$(function() {

    $('#sortDateFrom, #sortDateTo').change(function() {
      
        var startDate = $('#sortDateFrom option:selected').text();
        var endDate = $('#sortDateTo option:selected').text();
   
        if (startDate < endDate) {
            console.log("The beginning date must be smaller then the end date ");
        }
    });
});

＆＃13;

Issues with getting Selected values from drop down list

2 个答案: