hellojs-xiaotian
Version:
A clientside Javascript library for standardizing requests to OAuth2 web services (and OAuth1 - with a shim)
167 lines (147 loc) • 9.16 kB
JavaScript
var captionPlaceholder = {};
ko.bindingHandlers['options'] = {
'init': function(element) {
if (ko.utils.tagNameLower(element) !== "select")
throw new Error("options binding applies only to SELECT elements");
// Remove all existing <option>s.
while (element.length > 0) {
element.remove(0);
}
// Ensures that the binding processor doesn't try to bind the options
return { 'controlsDescendantBindings': true };
},
'update': function (element, valueAccessor, allBindings) {
function selectedOptions() {
return ko.utils.arrayFilter(element.options, function (node) { return node.selected; });
}
var selectWasPreviouslyEmpty = element.length == 0,
multiple = element.multiple,
previousScrollTop = (!selectWasPreviouslyEmpty && multiple) ? element.scrollTop : null,
unwrappedArray = ko.utils.unwrapObservable(valueAccessor()),
valueAllowUnset = allBindings.get('valueAllowUnset') && allBindings['has']('value'),
includeDestroyed = allBindings.get('optionsIncludeDestroyed'),
arrayToDomNodeChildrenOptions = {},
captionValue,
filteredArray,
previousSelectedValues = [];
if (!valueAllowUnset) {
if (multiple) {
previousSelectedValues = ko.utils.arrayMap(selectedOptions(), ko.selectExtensions.readValue);
} else if (element.selectedIndex >= 0) {
previousSelectedValues.push(ko.selectExtensions.readValue(element.options[element.selectedIndex]));
}
}
if (unwrappedArray) {
if (typeof unwrappedArray.length == "undefined") // Coerce single value into array
unwrappedArray = [unwrappedArray];
// Filter out any entries marked as destroyed
filteredArray = ko.utils.arrayFilter(unwrappedArray, function(item) {
return includeDestroyed || item === undefined || item === null || !ko.utils.unwrapObservable(item['_destroy']);
});
// If caption is included, add it to the array
if (allBindings['has']('optionsCaption')) {
captionValue = ko.utils.unwrapObservable(allBindings.get('optionsCaption'));
// If caption value is null or undefined, don't show a caption
if (captionValue !== null && captionValue !== undefined) {
filteredArray.unshift(captionPlaceholder);
}
}
} else {
// If a falsy value is provided (e.g. null), we'll simply empty the select element
}
function applyToObject(object, predicate, defaultValue) {
var predicateType = typeof predicate;
if (predicateType == "function") // Given a function; run it against the data value
return predicate(object);
else if (predicateType == "string") // Given a string; treat it as a property name on the data value
return object[predicate];
else // Given no optionsText arg; use the data value itself
return defaultValue;
}
// The following functions can run at two different times:
// The first is when the whole array is being updated directly from this binding handler.
// The second is when an observable value for a specific array entry is updated.
// oldOptions will be empty in the first case, but will be filled with the previously generated option in the second.
var itemUpdate = false;
function optionForArrayItem(arrayEntry, index, oldOptions) {
if (oldOptions.length) {
previousSelectedValues = !valueAllowUnset && oldOptions[0].selected ? [ ko.selectExtensions.readValue(oldOptions[0]) ] : [];
itemUpdate = true;
}
var option = element.ownerDocument.createElement("option");
if (arrayEntry === captionPlaceholder) {
ko.utils.setTextContent(option, allBindings.get('optionsCaption'));
ko.selectExtensions.writeValue(option, undefined);
} else {
// Apply a value to the option element
var optionValue = applyToObject(arrayEntry, allBindings.get('optionsValue'), arrayEntry);
ko.selectExtensions.writeValue(option, ko.utils.unwrapObservable(optionValue));
// Apply some text to the option element
var optionText = applyToObject(arrayEntry, allBindings.get('optionsText'), optionValue);
ko.utils.setTextContent(option, optionText);
}
return [option];
}
// By using a beforeRemove callback, we delay the removal until after new items are added. This fixes a selection
// problem in IE<=8 and Firefox. See https://github.com/knockout/knockout/issues/1208
arrayToDomNodeChildrenOptions['beforeRemove'] =
function (option) {
element.removeChild(option);
};
function setSelectionCallback(arrayEntry, newOptions) {
if (itemUpdate && valueAllowUnset) {
// The model value is authoritative, so make sure its value is the one selected
// There is no need to use dependencyDetection.ignore since setDomNodeChildrenFromArrayMapping does so already.
ko.selectExtensions.writeValue(element, ko.utils.unwrapObservable(allBindings.get('value')), true /* allowUnset */);
} else if (previousSelectedValues.length) {
// IE6 doesn't like us to assign selection to OPTION nodes before they're added to the document.
// That's why we first added them without selection. Now it's time to set the selection.
var isSelected = ko.utils.arrayIndexOf(previousSelectedValues, ko.selectExtensions.readValue(newOptions[0])) >= 0;
ko.utils.setOptionNodeSelectionState(newOptions[0], isSelected);
// If this option was changed from being selected during a single-item update, notify the change
if (itemUpdate && !isSelected) {
ko.dependencyDetection.ignore(ko.utils.triggerEvent, null, [element, "change"]);
}
}
}
var callback = setSelectionCallback;
if (allBindings['has']('optionsAfterRender') && typeof allBindings.get('optionsAfterRender') == "function") {
callback = function(arrayEntry, newOptions) {
setSelectionCallback(arrayEntry, newOptions);
ko.dependencyDetection.ignore(allBindings.get('optionsAfterRender'), null, [newOptions[0], arrayEntry !== captionPlaceholder ? arrayEntry : undefined]);
}
}
ko.utils.setDomNodeChildrenFromArrayMapping(element, filteredArray, optionForArrayItem, arrayToDomNodeChildrenOptions, callback);
ko.dependencyDetection.ignore(function () {
if (valueAllowUnset) {
// The model value is authoritative, so make sure its value is the one selected
ko.selectExtensions.writeValue(element, ko.utils.unwrapObservable(allBindings.get('value')), true /* allowUnset */);
} else {
// Determine if the selection has changed as a result of updating the options list
var selectionChanged;
if (multiple) {
// For a multiple-select box, compare the new selection count to the previous one
// But if nothing was selected before, the selection can't have changed
selectionChanged = previousSelectedValues.length && selectedOptions().length < previousSelectedValues.length;
} else {
// For a single-select box, compare the current value to the previous value
// But if nothing was selected before or nothing is selected now, just look for a change in selection
selectionChanged = (previousSelectedValues.length && element.selectedIndex >= 0)
? (ko.selectExtensions.readValue(element.options[element.selectedIndex]) !== previousSelectedValues[0])
: (previousSelectedValues.length || element.selectedIndex >= 0);
}
// Ensure consistency between model value and selected option.
// If the dropdown was changed so that selection is no longer the same,
// notify the value or selectedOptions binding.
if (selectionChanged) {
ko.utils.triggerEvent(element, "change");
}
}
});
// Workaround for IE bug
ko.utils.ensureSelectElementIsRenderedCorrectly(element);
if (previousScrollTop && Math.abs(previousScrollTop - element.scrollTop) > 20)
element.scrollTop = previousScrollTop;
}
};
ko.bindingHandlers['options'].optionValueDomDataKey = ko.utils.domData.nextKey();