[英]Adding an option to a select box, if the option is not already listed
我需要你的幫助,
如何在現有的javascript代碼中另外添加函數,這樣當field1中提供的新值未在選擇框中列出時,代碼將:
檢查(field1)值是否已在選擇框中列出,如果是,則在(field2)中選擇其值;
如果field1中提供的值未在選擇框(field2)中列出,則從(field1)添加新值並在(field2)中選擇它
這是一個小提琴: http : //jsfiddle.net/s66qg6xp/
編碼:
<!DOCTYPE html>
<html>
<head>
<script type="text/javascript">
function test() {
document.getElementById('field2').value = document.getElementById('field1').value
}
</script>
</head>
<body>
<input type="text" id="field1">
<br>
<select id="field2">
<option value="apples">apples</option>
<option value="oranges">oranges</option>
<option value="bananas">bananas</option>
</select>
<br>
<input type="button" value="test" onclick="test()">
</body>
</html>
所有JS:
<!DOCTYPE html>
<html>
<head>
<script type="text/javascript">
function test() {
var alreadyInList = [];
var allOptions = document.getElementsByTagName('option');
// populate already in list
for(var i = 0; i < allOptions.length; i++) {
alreadyInList[i] = allOptions[i].value;
}
var input = document.getElementById('field1').value;
for(var i = 0; i < allOptions.length; i++) {
if(alreadyInList.indexOf(input) > -1) {
// element is already in the list
} else {
alreadyInList.push(input);
var option = document.createElement('option');
option.value = input;
option.text = input;
document.getElementById('field2').appendChild(option);
}
}
}
</script>
</head>
<body>
<input type="text" id="field1">
<br>
<select id="field2">
<option value="apples">apples</option>
<option value="oranges">oranges</option>
<option value="bananas">bananas</option>
</select>
<br>
<input type="button" value="test" onclick="test()">
</body>
</html>
或者你可以用jQuery做到這一點:
<!DOCTYPE html>
<html>
<head>
<script src="jquery-2.1.3.min.js"></script>
<script type="text/javascript">
function test() {
var NewOption=document.getElementById("field1").value;
var options=$("#field2").children().filter(function (){return $(this).text()==NewOption});
if (options.length==0){
document.getElementById("field2").innerHTML=document.getElementById("field2").innerHTML+"<option value='"+NewOption+"'>"+NewOption+"</option>";
}
document.getElementById('field2').value = document.getElementById('field1').value;
}
</script>
</head>
<body>
<input type="text" id="field1">
<br>
<select id="field2">
<option value="apples">apples</option>
<option value="oranges">oranges</option>
<option value="bananas">bananas</option>
</select>
<br>
<input type="button" value="test" onclick="test()">
</body>
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