How to set default value for HTML select?

This question already has an answer here:

How can I set the default value for an HTML <select> element? 18 answers

---

$(function() {
    var temp="a"; 
    $("#MySelect").val(temp);
});

<select name="MySelect" id="MySelect">
    <option value="a">a</option>
    <option value="b">b</option>
    <option value="c">c</option>
</select>

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You first need to add values to your select options and for easy targetting give the select itself an id .

Let's make option b the default:

<select id="mySelect">
    <option>a</option>
    <option selected="selected">b</option>
    <option>c</option>
</select>

Now you can change the default selected value with JavaScript like this:

<script>
var temp = "a";
var mySelect = document.getElementById('mySelect');

for(var i, j = 0; i = mySelect.options[j]; j++) {
    if(i.value == temp) {
        mySelect.selectedIndex = j;
        break;
    }
}
</script>

See it in action on codepen .

---

您应该定义选项的属性，例如seleted =“selected”

<select>
   <option selected="selected">a</option>
   <option>b</option>
   <option>c</option>
</select>

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