以编程方式更改值时，Dojo选择onChange事件触发 [英] Dojo Select onChange event firing when changing value programmatically

问题描述

我有一个dojo（dijit）select下拉列表，它调用js函数onChange。我期望它仅在用户更改下拉列表中的值时才调用onChange函数，但是，当我以编程方式从js代码更改下拉列表的值时，它甚至调用onChange函数。我如何才能仅在用户更改下拉值时才调用该函数？当我以编程方式更改值时，它不应调用该函数。

I have a dojo (dijit) select dropdown that calls a js function onChange. I was expecting this to only call the onChange function when the user changes the value in the dropdown, however, it even calls the onChange function when I programmatically change the value of the dropdown from js code. How do I get it to only call the function when the user changes the dropdown value? It shouldn't call the function when I programmatically change the value.

<select jsId="ddlBoundaryType" id="ddlBoundaryType" name="ddlBoundaryType" 
                            dojoType="dijit.form.Select">
                            <option value="0">Circle</option>
                            <option value="1">Polygon</option>
                        </select>

dojo.addOnLoad(InitBoundaries);
    function InitBoundaries() {
        dojo.connect(dijit.byId("ddlBoundaryType"), 'onChange', Boundaries_ChangeBoundaryType); 
    }

推荐答案

我认为这种情况对您来说是 http://bugs.dojotoolkit.org/ticket/10594 ，因为它直接处理dijit.form.Select。当然，有几种方法可以解决此问题。

I think the proper fix in this case for you would be http://bugs.dojotoolkit.org/ticket/10594, since it deals directly with dijit.form.Select. Of course, there are a few ways to fix this.

1. 升级dojo：）。


2. 继承dijit.form.Select并修补 _updateSelection函数。


3. 扩展dijit.form.Select并将其直接修补在那里。

我会放弃第一个。第二种方法和第三种方法相似，因此我将使用第三种方法发布一个简单的解决方法，

I will forgo the first. The the second and the third method are similar, so I will just post a simple fix using the third way,

dijit.form.Select.extend({
   _updateSelection: function() {
        this.value = this._getValueFromOpts();
        var val = this.value;
        if(!dojo.isArray(val)){
            val = [val];
        }
        if(val && val[0]){
            dojo.forEach(this._getChildren(), function(child){
                var isSelected = dojo.some(val, function(v){
                    return child.option && (v === child.option.value);
                });
                dojo.toggleClass(child.domNode, this.baseClass + "SelectedOption", isSelected);
                dijit.setWaiState(child.domNode, "selected", isSelected);
            }, this);
        }
   }
});

请注意，我没有编写此函数，但我很高兴在源代码中将其the窃为最后一行，则this._handleOnChange（this.value）已删除。

Note that I did not write this function, I happily plagiarized it from the source code with the last line, this._handleOnChange(this.value) removed.

myWidget.attr('value', newValue, false) // should now work without firing onChange.

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