根据上一个下拉列表中选择的选项设置文本字段最小值和最大值

Question

我有一个下拉菜单，旁边有一个文本框。 在下拉列表中选择某个值时，文本框应允许基于所选选项的最小和最大字符数。 假设我选择选项 1，那么它旁边的文本框应该允许最少 10 个字符，最多 16 个字符。

如何实现？

<div class="row">
<div class="col-sm-6">
<div class="form-group">
<label class="required">Select Type</label>
<select class="form-control" id="prooftype">
<option value="0" disabled> </option>
<option value="name1">name1</option>
<option value="name2">name2</option>
<option value="name3">name3</option>
<option value="name4">name4</option>
</select>
</div>
</div>
<div class="col-sm-6">
<div class="form-group md-form">
<label class="required" for="id" data-error="wrong" data-success="right">
<i class="fa fa-info pr-2"></i> 
Enter Identity Card Number
</label>
<input id="id" type="number" minlength="3" class="form-control validate" autocomplete="off" onkeypress="return blockSpecialChar(event)" oninput="javascript: if (this.value.length > this.maxLength) this.value = this.value.slice(0, this.maxLength);" maxlength="20" />
</div>
</div>
</div>

Answer 1

你必须稍微改变一下你的代码

<div class="row">
<div class="col-sm-6">
<div class="form-group">
<label class="required">Select Type</label>
<select class="form-control" id="prooftype">
<option value="0/0" disabled> </option>
<option value="10/16">name1</option>
<option value="20/32">name2</option>
<option value="30/48">name3</option>
<option value="40/64">name4</option>
</select>
</div>
</div>
<div class="col-sm-6">
<div class="form-group md-form">
<label class="required" for="id" data-error="wrong" data-success="right">
<i class="fa fa-info pr-2"></i> 
Enter Identity Card Number
</label>
<input id="id" type="text" minlength="3" class="form-control validate" autocomplete="off" onkeypress="return blockSpecialChar(event)"  maxlength="20" />
</div>
</div>
</div>

和 jQuery

$('#prooftype').change(function(){
var tmp = $(this).val().split('/');
$('input#id').attr('minlength',tmp[0]).attr('maxlength',tmp[1]);
})

Answer 2

如果将12/16的选项值传递给后端，显然数据会反映。我认为你需要这样的东西：

<div class="row">
<div class="col-sm-6">
<div class="form-group">
<label class="required">Select Type</label>
<select class="form-control" id="prooftype">
<option value="0/0" disabled> </option>
<option value="name1">name1</option>
<option value="name2">name2</option>
<option value="name3">name3</option>
<option value="name4">name4</option>
</select>
</div>
</div>
<div class="col-sm-6">
<div class="form-group md-form">
<label class="required" for="id" data-error="wrong" data-success="right">
<i class="fa fa-info pr-2"></i> 
Enter Identity Card Number
</label>
<input id="inputid" type="text" minlength="3" class="form-control validate" autocomplete="off" onkeypress="return blockSpecialChar(event)"  maxlength="20" />
</div>
</div>
</div>

和你的 JQuery

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.4.1/jquery.min.js"></script>
<script type="text/javascript">
var selectedopt;
$('#prooftype').change(function(){
selectedopt=  $(this).val();
//Add your condition here, and  check the selected option value:
if(selectedopt== "name1")
{
//Set input min and max value based on the selected option value.
$('#inputid').attr('minlength','10').attr('maxlength','16');
}
elseif(selectedopt== "name2")
{
$('#inputid').attr('minlength','20').attr('maxlength','25');
}
// And so on........
})

</script>