Knockoutjs: bind dynamic iframes in foreach to par

问题:

I am trying to bind iframe and parent window so that I can change/update an observable in either the iframe or parent window and both views will update with new value.

Here is working sample: http://jsfiddle.net/NnT78/26/

I have tweaked some sample code that I have found and have it working great as follows;

HTML:

<iframe src="http://fiddle.jshell.net/zVPF8/11/show/" data-bind="bindIframe: $data"></iframe>

But when I put the same html in a foreach bind it get an error;

HTML:

<ul data-bind="foreach: iframes">
    <li>
        <iframe data-bind="attr: {src: src}, bindIframe: $data"></iframe>
    </li>
</ul>

Error:

Uncaught ReferenceError: Unable to parse bindings.
Bindings value: text: someProperty
Message: someProperty is not defined

Here is my Knockoutjs ViewModel code;

ko.bindingHandlers.bindIframe = {
  init: function(element, valueAccessor) {
    function bindIframe() {
        try {
            var iframeInit = element.contentWindow.initChildFrame,
                iframedoc = element.contentDocument.body;
        } catch(e) {
            // ignored
        }
        if (iframeInit)
            iframeInit(ko, valueAccessor());
        else if (iframedoc){
            ko.applyBindings(valueAccessor(), iframedoc);
        }
    };
    bindIframe();
    ko.utils.registerEventHandler(element, 'load', bindIframe);
  }
};

function ViewModel() {
    var self = this;
    self.someProperty = ko.observable(123);

    self.clickMe = function(data, event) {
        self.someProperty(self.someProperty() + 1);
    }

    self.anotherObservableArray = ko.observableArray([
        { name: "Bungle", type: "Bear" },
        { name: "George", type: "Hippo" },
        { name: "Zippy", type: "Unknown" }
    ]);

    self.iframes = ko.observableArray([
        { src: "http://fiddle.jshell.net/zVPF8/6/show/", type: "Bear" },
        { src: "http://fiddle.jshell.net/zVPF8/6/show/", type: "Hippo" },
        { src: "http://fiddle.jshell.net/zVPF8/6/show/", type: "Unknown" }
    ]);
};

// Bind outer doc
ko.applyBindings(new ViewModel());

See http://jsfiddle.net/NnT78/26/ for sample of single iframe working and dynamic iframes in foreach bind not working.

Thanks in advance!

回答1:

When in a foreach binding, $data is different; it's the current item in the array. You can fix your example by changing the iframe to bind to $root instead.

<iframe data-bind="attr: {src: src}, bindIframe: $root"></iframe>

http://jsfiddle.net/mbest/NnT78/29/