使用JQuery / Json填充选择列表的最佳方法是什么？ [英] Best way to populate select list with JQuery / Json?

问题描述

目前我们的开发团队使用这种模式，但我不禁想知道是否有更快或更高效的方法来完成相同的任务。

Currently our dev team uses this pattern, but I can't help but wonder if there is a faster or more html-efficient way of accomplishing the same task.

HTML

<select id="myList" style="width: 400px;">
</select>
<script id="myListTemplate" type="text/x-jQuery-tmpl">
        <option value="${idField}">${name}</option>
</script>

这是Javascript：

And this is the Javascript:

function bindList(url) {
    callAjax(url, null, false, function (json) {
        $('#myList').children().remove();
        $('#myListTemplate').tmpl(json.d).appendTo('#myList');
    });
}

推荐答案

这是我写的一个函数这样做。我不确定它是否比jQuery模板更快。 它一次创建和追加一个Option元素，这可能比模板慢。我怀疑模板构建了整个HTML字符串，然后一次性创建DOM元素。这可能会更快。 我想这个函数可以调整为做同样的事情。我使用过模板，我发现这个函数更容易用于填充Select列表这样简单的东西，它很适合我的utility.js文件。

This is a function I wrote to do just that. I'm not sure if it's faster than jQuery Templates. It creates and appends the Option elements one at a time, which may be slower than Templates. I suspect that Templates builds the whole HTML string, and then creates the DOM elements all in one shot. That may be a faster. I suppose this function could be adjusted to do the same thing. I've worked with Templates, and I do find that this function is easier to consume for something a simple as populating a Select list, and it fits nicely into my utility.js file.

更新：我更新了我的函数以首先构建HTML，并且只调用append（）一次。它实际上运行得更快。感谢您发布此问题，能够优化自己的代码非常好。

Update: I updated my function to build the HTML first, and call append() only once. It actually runs much faster now. Thanks for posting this question, it's nice to be able to optimize one's own code.

使用函数

 // you can easily pass in response.d from an AJAX call if it's JSON formatted
 var users = [ {id: 1, name: 'Alice'}, {id: 2, name: 'Bob'}, {id: 3, name: 'Cindy'} ]
 setSelectOptions($('#selectList'), users, 'id', 'name');

功能代码

// Fill a select list with options using an array of values as the data source
// @param {String, Object} selectElement Reference to the select list to be modified, either the selector string, or the jQuery object itself
// @param {Object} values An array of option values to use to fill the select list. May be an array of strings, or an array of hashes (associative arrays).
// @param {String} [valueKey] If values is an array of hashes, this is the hashkey to the value parameter for the option element
// @param {String} [textKey] If values is an array of hashes, this is the hashkey to the text parameter for the option element
// @param {String} [defaultValue] The default value to select in the select list
// @remark This function will remove any existing items in the select list
// @remark If the values attribute is an array, then the options will use the array values for both the text and value.
// @return {Boolean} false
function setSelectOptions(selectElement, values, valueKey, textKey, defaultValue) {

    if (typeof (selectElement) == "string") {
        selectElement = $(selectElement);
    }

    selectElement.empty();

    if (typeof (values) == 'object') {

        if (values.length) {

            var type = typeof (values[0]);
            var html = "";

            if (type == 'object') {
                // values is array of hashes
                var optionElement = null;

                $.each(values, function () {
                    html += '<option value="' + this[valueKey] + '">' + this[textKey] + '</option>';                    
                });

            } else {
                // array of strings
                $.each(values, function () {
                    var value = this.toString();
                    html += '<option value="' + value + '">' + value + '</option>';                    
                });
            }

            selectElement.append(html);
        }

        // select the defaultValue is one was passed in
        if (typeof defaultValue != 'undefined') {
            selectElement.children('option[value="' + defaultValue + '"]').attr('selected', 'selected');
        }

    }

    return false;

}

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