JavaScript 通过模式匹配实现重载_javascript技巧

/**
* 函数参数重载方法 overload，对函数参数进行模式匹配。默认的dispatcher支持*和...以及?，"*"表示一个任意类型的参数，"..."表示多个任意类型的参数，"?"一般用在",?..."表示0个或任意多个参数
* @method overload
* @static
* @optional {dispatcher} 用来匹配参数负责派发的函数
* @param {func_maps} 根据匹配接受调用的函数列表
* @return {function} 已重载化的函数
*/
overload: function(dispatcher, func_maps) {
if (! (dispatcher instanceof Function)) {
func_maps = dispatcher;
dispatcher = function(args) {
var ret = [];
return map(args, function(o) {return getType(o)}).join();
}
}

return function() {
var key = dispatcher([].slice.apply(arguments));
for (var i in func_maps) {
var pattern = new RegExp("^" + i.replace("*", "[^,]*").replace("...", ".*") + "$");
if (pattern.test(key)) {
return func_maps[i].apply(this, arguments);
}
}
};
},

getEx: function(obj, prop, returnJson) {
var ret, propType = ObjectH.getType(prop);
if (propType == 'array') {
if (returnJson) {
ret = {};
for (var i = 0; i & lt; prop.length; i++) {
ret[prop[i]] = ObjectH.getEx(obj, prop[i]);
}
} else {
//getEx(obj, props)
ret = [];
for (var i = 0; i & lt; prop.length; i++) {
ret[i] = ObjectH.getEx(obj, prop[i]);
}
}
} else {
//getEx(obj, prop)
var keys = (prop + "").split(".");
ret = obj;
for (var i = 0; i & lt; keys.length; i++) {
ret = ret[keys[i]];
}
if (returnJson) {
var json = {};
json[prop] = ret;
return json;
}
}
return ret;
},

getEx: FunctionH.overload({
"*,array,*": function(obj, prop, returnJson) {
if (returnJson) {
ret = {};
for (var i = 0; i & lt; prop.length; i++) {
ret[prop[i]] = ObjectH.getEx(obj, prop[i]);
}
} else {
ret = [];
for (var i = 0; i & lt; prop.length; i++) {
ret[i] = ObjectH.getEx(obj, prop[i]);
}
}
return ret;
},
"*,string,*": function(obj, prop, returnJson) {
var keys = (prop + "").split(".");
ret = obj;
for (var i = 0; i & lt; keys.length; i++) {
ret = ret[keys[i]];
}
if (returnJson) {
var json = {};
json[prop] = ret;
return json;
}
return ret;
}
}),

getEx: FunctionH.overload(function(args) {
return "prop is " + ObjectH.getType(args[1]);
},{
"prop is array": function(obj, prop, returnJson) {
if (returnJson) {
ret = {};
for (var i = 0; i & lt; prop.length; i++) {
ret[prop[i]] = ObjectH.getEx(obj, prop[i]);
}
} else {
//getEx(obj, props)
ret = [];
for (var i = 0; i & lt; prop.length; i++) {
ret[i] = ObjectH.getEx(obj, prop[i]);
}
}
return ret;
},
"prop is string": function(obj, prop, returnJson) {
var keys = (prop + "").split(".");
ret = obj;
for (var i = 0; i & lt; keys.length; i++) {
ret = ret[keys[i]];
}
if (returnJson) {
var json = {};
json[prop] = ret;
return json;
}
return ret;
}
}),

getEx: FunctionH.overload(function(args) {
return "prop is " + ObjectH.getType(args[1]) + " and returnJson is " +args[2];
},{
"prop is array and returnJson is true": function(obj, prop, returnJson) {
ret = {};
for (var i = 0; i & lt; prop.length; i++) {
ret[prop[i]] = ObjectH.getEx(obj, prop[i]);
}
return ret;
},
"prop is array and returnJson is false": function(obj, prop, returnJson) {
ret = [];
for (var i = 0; i & lt; prop.length; i++) {
ret[i] = ObjectH.getEx(obj, prop[i]);
}
return ret;
},
"prop is string and returnJson is true": function(obj, prop, returnJson) {
var keys = (prop + "").split(".");
ret = obj;
for (var i = 0; i & lt; keys.length; i++) {
ret = ret[keys[i]];
}
var json = {};
json[prop] = ret;
return json;
},
"prop is string and returnJson is false": function(obj, prop, returnJson) {
var keys = (prop + "").split(".");
ret = obj;
for (var i = 0; i & lt; keys.length; i++) {
ret = ret[keys[i]];
}
return ret;
}
}),

foo = FunctionH.overload(function() {
return MSIE ? "IE": "NotIE";
},{
"IE": function() {...}
"NotIE": function() {...}
});