如何获取带有data-dojo-attach-point的Dojo节点集的对象描述符？

Question

In one of my templates I have the following node:

<input data-dojo-attach-point="checkboxIsInternal" type="checkbox" checked />

I want to change the value of another property in the template's class to a certain value when this check is changed. So I thought in modifying the getter and setter for checkboxIsInternal's 'value' property so this happens automatically. Like this:

Object.defineProperty(this.checkboxIsInternal, 'value', {
    get: function() { return (this.clientType == 'I'); },
    set: function(v) { this.clientType = (v == 'on' ? 'I' : 'E'); },
    enumerable: true
});

but this hasn't worked. So I tried to console.log the descriptors of value property with

console.log(Object.getOwnPropertyDescriptor(this.checkboxIsInternal, 'value'));

but it showed undefined. Anyone knows why ?

If there are any other way to do this (changing one variable based on the change of a node) please let me know.

Answer 1

I don't know if Object.defineProperty works on an input element's value. If it does, what you're doing there is creating/retrieving expando properties on the checkbox itself, and you want to avoid those.

this.checkboxIsInternal should be a reference to your checkbox element if everything is set up right. Maybe try the old-fashioned way.

this.checkboxIsInternal.onchange = (function(e) {
    this.clientType = (this.checkboxIsInternal.checked) ? "I" : "E";
}).bind(this);

This will update the "clientType" property in your widget whenever the checkbox is checked/unchecked.

Answer 2

Dijit widgets provide the ability to write custom setters and getters, whose logic is executed when calling the set and get methods.

Custom setter methods are defined following the pattern _setFooAttr, where “foo” is the name of the property:

declare(_WidgetBase, {
    foo: "",
    _setFooAttr: function (value) {
        // custom logic, and update the foo property
    }
});

In similar way for can call your custom getter:

yourWidget.getFooAttr();