KnockoutJS中变量$data的由来和用途是什么? [英] What is the origin and purpose of the variable $data in KnockoutJS?

问题描述

在 KnockoutJS 教程中，我偶然发现了以下代码示例，其中包含无法解释的变量 $data.

In the KnockoutJS tutorials I stumbled upon the following code example that contains an unexplainable variable $data.

视图(html):

<!-- Folders -->
<ul class="folders" data-bind="template: { name: 'folderTemplate', foreach: folders }"></ul>
<script type="text/html" id="folderTemplate">
    <li data-bind="css: { selected: $data == mailViewModel.selectedFolder() },
                   click: function() { mailViewModel.selectFolder($data) }">
        ${$data}
    </li>    
</script>

视图模型 (JavaScript):

The View Model (JavaScript):

var viewModel = {
    // Data
    folders: ['Inbox', 'Archive', 'Sent', 'Spam'],
    selectedFolder: ko.observable('Inbox'),

    // Behaviours
    selectFolder: function (folder) {
        this.selectedFolder(folder);
    }    
};

window.mailViewModel = viewModel;
ko.applyBindings(viewModel);

本教程不包含任何解释该美元符号的用途以及此 $data 的来源.变量 $data 未定义，当我将 $data 的所有三个实例重命名为 $foobar 时，该示例不再起作用.

The tutorial does not contain any explanation what that dollar sign is used for and where this $data comes from. The variable $data is nowhere defined and when I rename all three instances of $data to $foobar, the example does not work anymore.

这里发生了什么样的魔法?

What kind of magic is going on here?

推荐答案

$data 变量是一个内置变量，用于引用当前绑定的对象.在示例中，这是 viewModel.folders 数组中的元素之一.

The $data variable is a built-in variable used to refer to the current object being bound. In the example this is the one of the elements in the viewModel.folders array.

这篇关于KnockoutJS中变量$data的由来和用途是什么?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！