knockout.js - 在 viewModel 范围之外的 javascript 函数中访问 viewModel

Question

我想知道是否可以从 viewModel 本身范围之外的方法访问 knockout.js 主 viewModel。举个例子:

function Employee(data) {
  var self = this;
  ko.mapping.fromJS(data, {}, this);
}

function EmployeeViewModel() {
  var self = this;
  this.employees = ko.observableArray([]);

  this.loadEmployees = function() {
    var mappedEmployees= $.map(JSON.parse(data.value), function(item) { return new Employee(item) });
    self.employees (mappedEmployees);
  }
}

// here's the part I'm curious about
$(document).ready(function() {
  ko.applyBindings(new EmployeeViewModel());  

  $("#myLink").click(function() {
     // is there some way to get back into the ko context here?
     // like with ko.dataFor or ko.contextFor?
  });
}

Answer 1

您始终可以通过将 View 模型存储在您可以访问的变量中来访问它，module and revealing module patterns很好，但是您可以将其存储在不会与其他名称冲突的对象中(此处为“我的”):

my = { viewModel: new EmployeeViewModel() };
ko.applyBindings(my.viewModel);

您的想法是正确的，您只需将元素作为 click 函数的参数并将 target 属性传递给 ko.dataFor 或 ko.contextFor ( jsfiddle ):

$(document).ready(function() {
    my.vm = new EmployeeViewModel();
    ko.applyBindings(my.vm);
    $('button').on('click', function(e) {
        alert('you clicked on employee ' + ko.contextFor(e.target).$data.name() +
             ' also known as ' + ko.dataFor(e.target).name());
    });
});​

不使用jQuery绑定(bind)点击事件，你总是可以使用the Knockout click binding ，它将当前模型数据作为第一个参数传递，将事件作为第二个参数传递(jsfiddle):

function EmployeeViewModel() {
  var self = this;

  // skipped some of your code

  this.clickedOnEmployee = function(model, event) {
    // assuming your Employee has a name observable
    alert('You clicked on employee ' + model.name());
  };
}

在您的 html 中( $root 是您的基本 View 模型，如果您的 clickedOnEmployee 函数在您的 Employee 对象上，则不需要它):

<ul data-bind="foreach: employees">
    <li>
        <span data-bind="text: name"></span>
        <button data-bind="click: $root.clickedOnEmployee">show</button>
    </li>
</ul>