我在JavaScript 学习如何基于 var typeSelectBox = "<select id='depprojsDevice' class='selectpicker'>";
typeSelectBox += "<option value=''> -- SELECT --</option>";
if (arr) {
for (var i in arr) {
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如何使选择表单为必填项?我尝试了“需要”,但它不起作用。 <div class="form-group">
<label for="sel2">How many years have you been trading *</label>
<select class="form-control" id="sel2" required>
<option>Please s