在多重继承级别的情况下,此函数可以用作其他语言的super()方法。这是一个演示小提琴,带有一些测试,您可以在方法内部使用这样使用它:call_base(this, 'method_name', arguments);
它利用了最新的ES功能,因此无法保证与旧版浏览器的兼容性。在IE11,FF29,CH35中测试。
/**
* Call super method of the given object and method.
* This function create a temporary variable called "_call_base_reference",
* to inspect whole inheritance linage. It will be deleted at the end of inspection.
*
* Usage : Inside your method use call_base(this, 'method_name', arguments);
*
* @param {object} object The owner object of the method and inheritance linage
* @param {string} method The name of the super method to find.
* @param {array} args The calls arguments, basically use the "arguments" special variable.
* @returns {*} The data returned from the super method.
*/
function call_base(object, method, args) {
// We get base object, first time it will be passed object,
// but in case of multiple inheritance, it will be instance of parent objects.
var base = object.hasOwnProperty('_call_base_reference') ? object._call_base_reference : object,
// We get matching method, from current object,
// this is a reference to define super method.
object_current_method = base[method],
// Temp object wo receive method definition.
descriptor = null,
// We define super function after founding current position.
is_super = false,
// Contain output data.
output = null;
while (base !== undefined) {
// Get method info
descriptor = Object.getOwnPropertyDescriptor(base, method);
if (descriptor !== undefined) {
// We search for current object method to define inherited part of chain.
if (descriptor.value === object_current_method) {
// Further loops will be considered as inherited function.
is_super = true;
}
// We already have found current object method.
else if (is_super === true) {
// We need to pass original object to apply() as first argument,
// this allow to keep original instance definition along all method
// inheritance. But we also need to save reference to "base" who
// contain parent class, it will be used into this function startup
// to begin at the right chain position.
object._call_base_reference = base;
// Apply super method.
output = descriptor.value.apply(object, args);
// Property have been used into super function if another
// call_base() is launched. Reference is not useful anymore.
delete object._call_base_reference;
// Job is done.
return output;
}
}
// Iterate to the next parent inherited.
base = Object.getPrototypeOf(base);
}
}
ParentClass.prototype.myMethod.apply() or
像处理构造函数那样执行ParentClass.prototype.myMethod.call()`。