问题
I thought that adding a \"value\" attribute set on the <select> element below would cause the <option> containing my provided \"value\" to be selected by default:
<select name=\"hall\" id=\"hall\" value=\"3\">
<option>1</option>
<option>2</option>
<option>3</option>
<option>4</option>
<option>5</option>
</select>However, this did not work as I had expected. How can I set which <option> element is selected by default?
回答1:
Set selected="selected" for the option you want to be the default.
<option selected="selected">
3
</option>
回答2:
In case you want to have a default text as a sort of placeholder/hint but not considered a valid value (something like "complete here", "select your nation" ecc.) you can do something like this:
<select>
<option value="" selected disabled hidden>Choose here</option>
<option value="1">One</option>
<option value="2">Two</option>
<option value="3">Three</option>
<option value="4">Four</option>
<option value="5">Five</option>
</select>回答3:
Complete example:
<select name="hall" id="hall">
<option>
1
</option>
<option>
2
</option>
<option selected>
3
</option>
<option>
4
</option>
<option>
5
</option>
</select> 回答4:
I came across this question, but the accepted and highly upvoted answer didn't work for me. It turns out that if you are using React, then setting selected doesn't work.
Instead you have to set a value in the <select> tag directly as shown below:
<select value="B">
<option value="A">Apple</option>
<option value="B">Banana</option>
<option value="C">Cranberry</option>
</select>
Read more about why here on the React page.
回答5:
You can do it like this:
<select name="hall" id="hall">
<option> 1 </option>
<option> 2 </option>
<option selected> 3 </option>
<option> 4 </option>
<option> 5 </option>
</select>
Provide "selected" keyword inside the option tag, which you want to appear by default in your drop down list.
Or you can also provide attribute to the option tag i.e.
<option selected="selected">3</option>
回答6:
if you want to use the values from a Form and keep it dynamic try this with php
<form action="../<SamePage>/" method="post">
<?php
$selected = $_POST['select'];
?>
<select name="select" size="1">
<option <?php if($selected == '1'){echo("selected");}?>>1</option>
<option <?php if($selected == '2'){echo("selected");}?>>2</option>
</select>
</form>
回答7:
I prefer this:
<select>
<option selected hidden>Choose here</option>
<option value="1">One</option>
<option value="2">Two</option>
<option value="3">Three</option>
<option value="4">Four</option>
<option value="5">Five</option>
</select>
'Choose here' disappears after an option has been selected.
回答8:
An improvement for nobita's answer. Also you can improve the visual view of the drop down list, by hiding the element 'Choose here'.
<select>
<option selected disabled hidden>Choose here</option>
<option value="1">One</option>
<option value="2">Two</option>
<option value="3">Three</option>
<option value="4">Four</option>
<option value="5">Five</option>
</select>回答9:
Another example; using JavaScript to set a selected option.
(You could use this example to for loop an array of values into a drop down component)
<select id="yourDropDownElementId"><select/>
// Get the select element
var select = document.getElementById("yourDropDownElementId");
// Create a new option element
var el = document.createElement("option");
// Add our value to the option
el.textContent = "Example Value";
el.value = "Example Value";
// Set the option to selected
el.selected = true;
// Add the new option element to the select element
select.appendChild(el);
回答10:
Best way in my opinion:
<select>
<option value="" selected="selected" hidden="hidden">Choose here</option>
<option value="1">One</option>
<option value="2">Two</option>
<option value="3">Three</option>
<option value="4">Four</option>
<option value="5">Five</option>
</select>
Why not disabled?
When you use disabled attribute together with <button type="reset">Reset</button> value is not reset to original placeholder. Instead browser choose first not disabled option which may cause user mistakes.
Default empty value
Every production form have validation, then empty value should not be a problem. This way we may have empty not required select.
XHTML syntax attributes
selected="selected" syntax is the only way to be compatible with both XHTML and HTML 5. It is correct XML syntax and some editors may be happy about this. It is more backward compatible. I do not have strong feeling about this, but if above-mention arguments are your requirements you should follow full syntax.
回答11:
The selected attribute is a boolean attribute.
When present, it specifies that an option should be pre-selected when the page loads.
The pre-selected option will be displayed first in the drop-down list.
<select>
<option value="volvo">Volvo</option>
<option value="saab">Saab</option>
<option value="vw">VW</option>
<option value="audi" selected>Audi</option>
</select>
回答12:
If you are in react you can use defaultValue as attribute instead of value in the select tag.
回答13:
If you are using select with angular 1, then you need to use ng-init, otherwise, second option will not be selected since, ng-model overrides the defaul selected value
<select ng-model="sortVar" ng-init='sortVar="stargazers_count"'>
<option value="name">Name</option>
<option selected="selected" value="stargazers_count">Stars</option>
<option value="language">Language</option>
</select>
回答14:
I used this php function to generate the options, and insert it into my HTML
<?php
# code to output a set of options for a numeric drop down list
# parameters: (start, end, step, format, default)
function numericoptions($start, $end, $step, $formatstring, $default)
{
$retstring = "";
for($i = $start; $i <= $end; $i = $i + $step)
{
$retstring = $retstring . '<OPTION ';
$retstring = $retstring . 'value="' . sprintf($formatstring,$i) . '"';
if($default == $i)
{
$retstring = $retstring . ' selected="selected"';
}
$retstring = $retstring . '>' . sprintf($formatstring,$i) . '</OPTION> ';
}
return $retstring;
}
?>
And then in my webpage code I use it as below;
<select id="endmin" name="endmin">
<?php echo numericoptions(0,55,5,'%02d',$endmin); ?>
</select>
If $endmin is created from a _POST variable every time the page is loaded (and this code is inside a form which posts) then the previously selected value is selected by default.
回答15:
value attribute of tag is missing, so it doesn't show as u desired selected. By default first option show on dropdown page load, if value attribute is set on tag.... I got solved my problem this way
回答16:
This code sets the default value for the HTML select element with PHP.
<select name="hall" id="hall">
<?php
$default = 3;
$nr = 1;
while($nr < 10){
if($nr == $default){
echo "<option selected=\"selected\">". $nr ."</option>";
}
else{
echo "<option>". $nr ."</option>";
}
$nr++;
}
?>
</select>
回答17:
You can use:
<option value="someValue" selected>Some Value</option>
instead of,
<option value="someValue" selected = "selected">Some Value</option>
both are equally correct.
回答18:
I would just simply make the first select option value the default and just hide that value in the dropdown with HTML5's new "hidden" feature. Like this:
<select name="" id="">
<option hidden value="default">Select An Option</option>
<option value="1">One</option>
<option value="2">Two</option>
<option value="3">Three</option>
<option value="4">Four</option>
</select>
回答19:
I myself use it
<select selected=''>
<option value=''></option>
<option value='1'>ccc</option>
<option value='2'>xxx</option>
<option value='3'>zzz</option>
<option value='4'>aaa</option>
<option value='5'>qqq</option>
<option value='6'>wwww</option>
</select>
回答20:
You just need to put attribute "selected" on a particular option instead direct to select element.
Here is snippet for same and multiple working example with different values.
Select Option 3 :-
<select name="hall" id="hall">
<option>1</option>
<option>2</option>
<option selected="selected">3</option>
<option>4</option>
<option>5</option>
</select>
<br/>
<br/>
<br/>
Select Option 5 :-
<select name="hall" id="hall">
<option>1</option>
<option>2</option>
<option>3</option>
<option>4</option>
<option selected="selected">5</option>
</select>
<br/>
<br/>
<br/>
Select Option 2 :-
<select name="hall" id="hall">
<option>1</option>
<option selected="selected">2</option>
<option>3</option>
<option>4</option>
<option>5</option>
</select>回答21:
The problem with <select> is, it's sometimes disconnected with the state of what's currently rendered and unless something has changed in the option list, no change value is returned. This can be a problem when trying to select the first option from a list. The following code can get the first-option the first-time selected, but onchange="changeFontSize(this)" by its self would not. There are methods described above using a dummy option to force a user to make a change value to pickup the actual first value, such as starting the list with an empty value. Note: onclick would call the function twice, the following code does not, but solves the first-time problem.
<label>Font Size</label>
<select name="fontSize" id="fontSize" onfocus="changeFontSize(this)" onchange="changeFontSize(this)">
<option value="small">Small</option>
<option value="medium">Medium</option>
<option value="large">Large</option>
<option value="extraLarge">Extra large</option>
</select>
<script>
function changeFontSize(x){
body=document.getElementById('body');
if (x.value=="extraLarge") {
body.style.fontSize="25px";
} else {
body.style.fontSize=x.value;
}
}
</script>
回答22:
This is how I did it...
<form action="../<SamePage>/" method="post">
<?php
if ( $_POST['drop_down'] == "")
{
$selected = "";
}
else
{
$selected = "selected";
}
?>
<select name="select" size="1">
<option value="1" <?php $selected ?>>One</option>
//////// OR ////////
<option value="2" $selected>Two</option>
</select>
</form>
回答23:
I use Angular and i set the default option by
HTML Template
<select #selectConnection [(ngModel)]="selectedVal" class="form-control col-sm-6 " max-width="100px" title="Select"
data-size="10">
<option >test1</option>
<option >test2</option>
</select>
Script:
sselectedVal:any="test1";
回答24:
You can try like this
<select name="hall" id="hall">
<option>1</option>
<option>2</option>
<option selected="selected">3</option>
<option>4</option>
<option>5</option>
</select>
来源：https://stackoverflow.com/questions/3518002/how-can-i-set-the-default-value-for-an-html-select-element