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[英]Output the differences of two array values from a dropdown menu (Javascript)
[英]Two dropdown values from an array using JavaScript
簡單的問題:我想使用JavaScript在HTML中的兩個下拉列表中循環數組值。 但只有一個下拉列表正在運行。 如果我評論一個,另一個工作。 我想填寫下拉列表中的值。 這個簡單的代碼有什么問題?
var select = document.getElementById("selectNumber"); var select2 = document.getElementById("selectNumber2"); var options = ["1", "2", "3", "4", "5"]; for (var i = 0; i < options.length; i++) { var opt = options[i]; var el = document.createElement("option"); el.textContent = opt; el.value = opt; select.appendChild(el); select2.appendChild(el); }
<select id="selectNumber"> <option>Choose a number</option> </select> <select id="selectNumber2"> <option>Choose a number</option> </select>
不要對兩個控件使用相同的元素。 首先克隆它
var select = document.getElementById("selectNumber"); var select2 = document.getElementById("selectNumber2"); var options = ["1", "2", "3", "4", "5"]; for (var i = 0; i < options.length; i++) { var opt = options[i]; var el = document.createElement("option"); el.textContent = opt; el.value = opt; select.appendChild(el); select2.appendChild(el.cloneNode(true)); }
<select id="selectNumber"> <option>Choose a number</option> </select> <select id="selectNumber2"> <option>Choose a number</option> </select>
為每個select創建一個option元素,appendChild不克隆元素,所以第二個append從第一個元素中獲取元素
var select = document.getElementById("selectNumber"); var select2 = document.getElementById("selectNumber2"); var options = ["1", "2", "3", "4", "5"]; for (var i = 0; i < options.length; i++) { var opt = options[i]; var el = document.createElement("option"); el.textContent = opt; el.value = opt; var el1 = document.createElement("option"); el1.textContent = opt; el1.value = opt; select.appendChild(el1); select2.appendChild(el); }
<select id="selectNumber"> <option>Choose a number</option> </select> <select id="selectNumber2"> <option>Choose a number</option> </select>
var select = document.getElementById("selectNumber"); var select2 = document.getElementById("selectNumber2"); var options = ["1", "2", "3", "4", "5"]; for(var i = 0; i < options.length; i++) { var opt = options[i]; var el = document.createElement("option"); el.textContent = opt; el.value = opt; select.appendChild(el); var el2 = document.createElement("option"); el2.textContent = opt; el2.value = opt; select2.appendChild(el2); }
<select id="selectNumber"> <option>Choose a number</option> </select> <select id="selectNumber2"> <option>Choose a number</option> </select>
創建兩個不同的節點並添加它們。
您的代碼無效的原因在於此處
希望這可以幫助 :)
您可以使用JavaScript和jQuery:
var options = ["1", "2", "3", "4", "5"]; $.each(options, function(key, value) { $('#selectNumber,#selectNumber2').append($("<option/>", { value: key, text: value })); });
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script> <select id="selectNumber"> <option>Choose a number1</option> </select> <select id="selectNumber2"> <option>Choose a number2</option> </select>
這是JavaScript代碼:
<script>
var select = document.getElementById("selectNumber");
var select2 = document.getElementById("selectNumber2");
var options = ["1", "2", "3", "4", "5"];
for (var i = 0; i < options.length; i++) {
var opt = options[i];
var el = document.createElement("option");
el.textContent = opt;
el.value = opt;
select.appendChild(el);
select2.appendChild(el.cloneNode(true));
}
});
</script>
如果您想要單獨選項代碼,這是另一種選擇
<script>
var select = document.getElementById("selectNumber");
var select2 = document.getElementById("selectNumber2");
var options = ["1", "2", "3", "4", "5"];
for (var i = 0; i < options.length; i++) {
var opt = options[i];
var el = document.createElement("option");
el.textContent = opt;
el.value = opt;
select.appendChild(el);
var e2 = document.createElement("option");
e2.textContent = opt;
e2.value = opt;
select2.appendChild(e2);
}
</script>
這是沒有克隆的方法( jsFiddle ):
var select = document.getElementById("selectNumber");
var select2 = document.getElementById("selectNumber2");
var options = ["1", "2", "3", "4", "5"];
for (var i = 0; i < options.length; i++) {
var opt = options[i];
select.add(new Option(opt,opt));
select2.add(new Option(opt,opt));
}
在此處閱讀有關JavaScript add
功能的更多信息。
問題是您創建的元素只能附加在一個父元素中。 不是都。 咆哮有效的代碼片段
var select2 = document.getElementById("selectNumber2");
var options = ["1", "2", "3", "4", "5"];
for (var i = 0; i < options.length; i++) {
var opt = options[i];
var el = document.createElement("option");
el.textContent = opt;
el.value = opt;
select.appendChild(el);
var copy = el.cloneNode(true);
select2.appendChild(copy);
}
只需注意行var copy = el.cloneNode(true);
這將創建元素的新克隆,然后將其附加到另一個select
。
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