javascript 将列表框中的所有选项转换为逗号分隔的字符串的惯用 jQuery？
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Idiomatic jQuery to get all options in a listbox into comma-separated string?
提问by Cade Roux
Where lb is a listbox, txtfield is a textbox, this code takes all the values of the options, puts them in an array and makes it into a comma-separated list:
其中 lb 是一个列表框，txtfield 是一个文本框，此代码获取选项的所有值，将它们放入一个数组中并使其成为一个逗号分隔的列表：
var arr = [];
for (var i = 0; i < lb.length; i++) {
arr[i] = lb.options[i].value;
}
txtfield.value = arr.join(',');
lb.options.toString() obviously doesn't work because it's an array of options (value and text). I haven't found anything more succint than this.
lb.options.toString() 显然不起作用，因为它是一组选项（值和文本）。我还没有找到比这更简洁的东西。
What's the jQuery way to do this? I tried messing around with $(lb).each(), but can't seem to get it to work in the same way.
什么是 jQuery 方法来做到这一点？我尝试使用$(lb).each()，但似乎无法以相同的方式工作。
回答by user113716
txtfield.value = $(lb.options).map(function() {
return this.value;
}).get().join(',');
This uses .map()to create a jQuery object by returning the valueof each option, then uses .get()to extract the Array from the object.
这用于.map()通过返回valueeach 的来创建一个 jQuery 对象option，然后用于.get()从对象中提取 Array。
EDIT:As @Nick Cravernoted in the comment below, if you need to get optimal performance (with jQuery), it makes more sense to use the $.map()variationsince you already have a collection. See his answerfor details.
编辑：作为@Nick Craver在下面的评论指出，如果需要获得最佳性能（使用jQuery），它使得使用更有意义的$.map()变化，因为你已经有一个集合。详情见他的回答。
EDIT:To get better performance, do your forloop, but cache the references to the properties. It makes a difference.
编辑：为了获得更好的性能，请执行for循环，但缓存对属性的引用。它有所作为。
var arr = [], opts = lb.options, len = opts.length;
for (var i = 0; i < len; i++) {
arr[i] = opts[i].value;
}
txtfield.value = arr.join(',');
回答by Nick Craver
The jQuery version is .map()like this:
jQuery 版本是.map()这样的：
var arr = $(lb).find("option").map(function() { return this.value; }).get();
txtfield.value = arr.join(',');
Or a bit faster with $.map()like this:
或者$.map()像这样更快一点：
var arr = $.map(lb.options, function(o) { return o.value; });
txtfield.value = arr.join(',');
However, both are significantly less efficientthan a forloop, go with the plain JavaScript version you already have.
然而，无论是显著低效率比for循环，你已经拥有了普通的JavaScript版本去。
回答by Quintin Robinson
回答by jwueller
This is the jQuery equivalent to your code. There are more elegant solutions, though.
这是与您的代码等效的 jQuery。不过，还有更优雅的解决方案。
var values = [];
$(lb).children('option').each(function () {
values.push($(this).text());
});
$(txtfield).val(values.join(','));
回答by El Ronnoco
Could do it like this but I'm not sure what you're trying to achieve?
可以这样做，但我不确定你想要达到什么目标？
$('option', $(lb)).each(function() { arr.push($(this).text()) });
回答by Jaydeep Shil
See demo here: Fiddler Demo
在此处查看演示：Fiddler 演示
you can get the multiple selected option Text values with separator.
您可以使用分隔符获取多个选定选项文本值。
$('#testID').change(function () {
var test=$(this).find("option:selected").map(function () {
return $(this).text();
}).get().join('//');
alert(test);
});<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<select id="testID" multiple="multiple">
<option value="1">test Value1</option>
<option value="2">test Value2</option>
<option value="3">test Value3</option>
<option value="4">test Value4</option>
<option value="5">test Value5</option>
<option value="6">test Value6</option>
</select>
<input type="button" value="Get dropdown selected Value" id="select-values">
<div id="result"></div>