/
selectExtensions.js
80 lines (76 loc) · 4.41 KB
/
selectExtensions.js
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(function () {
var hasDomDataExpandoProperty = '__ko__hasDomDataOptionValue__';
// Normally, SELECT elements and their OPTIONs can only take value of type 'string' (because the values
// are stored on DOM attributes). ko.selectExtensions provides a way for SELECTs/OPTIONs to have values
// that are arbitrary objects. This is very convenient when implementing things like cascading dropdowns.
ko.selectExtensions = {
readValue : function(element) {
switch (ko.utils.tagNameLower(element)) {
case 'option':
if (element[hasDomDataExpandoProperty] === true)
return ko.utils.domData.get(element, ko.bindingHandlers.options.optionValueDomDataKey);
return ko.utils.ieVersion <= 7
? (element.getAttributeNode('value') && element.getAttributeNode('value').specified ? element.value : element.text)
: element.value;
case 'select':
return element.selectedIndex >= 0 ? ko.selectExtensions.readValue(element.options[element.selectedIndex]) : undefined;
default:
return element.value;
}
},
writeValue: function(element, value, allowUnset) {
switch (ko.utils.tagNameLower(element)) {
case 'option':
switch(typeof value) {
case "string":
ko.utils.domData.set(element, ko.bindingHandlers.options.optionValueDomDataKey, undefined);
if (hasDomDataExpandoProperty in element) { // IE <= 8 throws errors if you delete non-existent properties from a DOM node
delete element[hasDomDataExpandoProperty];
}
element.value = value;
break;
default:
// Store arbitrary object using DomData
ko.utils.domData.set(element, ko.bindingHandlers.options.optionValueDomDataKey, value);
element[hasDomDataExpandoProperty] = true;
// Special treatment of numbers is just for backward compatibility. KO 1.2.1 wrote numerical values to element.value.
element.value = typeof value === "number" ? value : "";
break;
}
break;
case 'select':
if (value === "" || value === null) // A blank string or null value will select the caption
value = undefined;
var selection = -1;
for (var i = 0, n = element.options.length, optionValue; i < n; ++i) {
optionValue = ko.selectExtensions.readValue(element.options[i]);
// Include special check to handle selecting a caption with a blank string value
if (optionValue == value || (optionValue === "" && value === undefined)) {
selection = i;
break;
}
}
if (allowUnset || selection >= 0 || (value === undefined && element.size > 1)) {
element.selectedIndex = selection;
if (ko.utils.ieVersion === 6) {
// Workaround for IE6 bug: It won't reliably apply values to SELECT nodes during the same execution thread
// right after you've changed the set of OPTION nodes on it. So for that node type, we'll schedule a second thread
// to apply the value as well.
ko.utils.setTimeout(function () {
element.selectedIndex = selection;
}, 0);
}
}
break;
default:
if ((value === null) || (value === undefined))
value = "";
element.value = value;
break;
}
}
};
})();
ko.exportSymbol('selectExtensions', ko.selectExtensions);
ko.exportSymbol('selectExtensions.readValue', ko.selectExtensions.readValue);
ko.exportSymbol('selectExtensions.writeValue', ko.selectExtensions.writeValue);