// Internet Explorer Test Pages Copyright © 2012 Microsoft Corporation. All rights reserved.
//
// Redistribution and use in source and binary forms, with or without modification,
// are permitted provided that the following conditions are met:
//
// Redistributions of source code must retain the above copyright notice, this list of
// conditions and the following disclaimer.
//
// Redistributions in binary form must reproduce the above copyright notice, this list of
// conditions and the following disclaimer in the documentation and/or other materials
// provided with the distribution.
//
// Neither the name of the Microsoft Corporation nor the names of its contributors may be
// used to endorse or promote products derived from this software without specific prior
// written permission.
//
// THIS SOFTWARE IS PROVIDED BY MICROSOFT CORPORATION "AS IS" AND ANY EXPRESS OR IMPLIED
// WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
// FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL MICROSOFT CORPORATION
// BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
// LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
// OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
// OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
// POSSIBILITY OF SUCH DAMAGE.
// This function returns the value of an API feature if it is defined with one of
// the known ventor prefixes.
//
// Parameters:
// parent: the object containing the API feature
// feature: the name of the API feature, this should be a string value
// isAttribute: set this to true to indicate that this is a constant attribute
// as opposed to a variable
function BrowserHasFeature(parent, feature, isAttribute)
{
if (parent[feature] !== undefined)
{
//feature is defined without a vendor prefix, no further checks necessary
return parent[feature];
}
// the feature is not defined without a vendor prefix, so find the vendor prefix, if any,
// that it is defined with
var prefix = GetVendorPrefix(parent, feature, isAttribute);
// if prefix is not undefined, then the feature has been found to exist with this prefix
if (prefix !== undefined)
{
var prefixedFeatureName = AppendPrefix(prefix, feature, isAttribute);
return parent[prefixedFeatureName];
}
//The feature does not exist.
//Callers should check for !==undefined as the feature itself could return
//a Bool which would fail a typical if(feature) check
return undefined;
}
// This function returns the vendor prefix found if a certain feature is defined with it.
// It takes the same parameters at BrowserHasFeature().
function GetVendorPrefix(parent, feature, isAttribute)
{
//Known vendor prefixes
var VendorPrefixes = ["moz", "ms", "o", "webkit"];
for (vendor in VendorPrefixes)
{
//Build up the new feature name with the vendor prefix
var prefixedFeatureName = AppendPrefix(VendorPrefixes[vendor], feature, isAttribute);
if (parent[prefixedFeatureName] !== undefined)
{
//Vendor prefix version exists, return a pointer to the feature
return VendorPrefixes[vendor];
}
}
// if no version of the feature with a vendor prefix has been found, return undefined
return undefined;
}
// This will properly capitalize the feature name and then return the feature name preceded
// with the provided vendor prefix. If the prefix given is undefined, this function will
// return the feature name given as is. The output of this function should not be used
// as an indicator of whether or not a feature exists as it will return the same thing if
// the inputted feature is undefined or is defined without a vendor prefix. It takes the
// same parameters at BrowserHasFeature().
function AppendPrefix(prefix, feature, isAttribute)
{
if (prefix !== undefined)
{
if (isAttribute)
{
// if a certain feature is an attribute, then it follows a different naming standard
// where it must be completely capitalized and have words split with an underscore
return prefix.toUpperCase() + "_" + feature.toUpperCase();
}
else
{
//Vendor prefixing should follow the standard convention: vendorprefixFeature
//Note that the feature is capitalized after the vendor prefix
//Therefore if the feature is window.feature, the vendor prefix version is:
//window.[vp]Feature where vp is the vendor prefix:
//window.msFeature, window.webkitFeature, window.mozFeature, window.oFeature
var newFeature = feature[0].toUpperCase() + feature.substr(1, feature.length);
//Build up the new feature name with the vendor prefix
return prefix + newFeature;
}
}
else
{
return feature;
}
}