UnderscoreJS 先將所有的函數宣告在前面
_.map = _.collect = function(obj, iterator, context) {
...
_.reduce = _.foldl = _.inject = function(obj, iterator, memo, context) {
...接著在最下面，將所有的函數加到 _ 的原型上並綁定 _wrapper
_.mixin = function(obj) {
each(_.functions(obj), function(name) {
var func = _[name] = obj[name];
_.prototype[name] = function() {
var args = [this._wrapped];
push.apply(args, arguments);
return result.call(this, func.apply(_, args));
};
});
};
...
// Add all of the Underscore functions to the wrapper object.
_.mixin(_);
// Add all mutator Array functions to the wrapper.
each(['pop', 'push', 'reverse', 'shift', 'sort', 'splice', 'unshift'], function(name) {
var method = ArrayProto[name];
_.prototype[name] = function() {
var obj = this._wrapped;
method.apply(obj, arguments);
if ((name == 'shift' || name == 'splice') && obj.length === 0) delete obj[0];
return result.call(this, obj);
};
});
// Add all accessor Array functions to the wrapper.
each(['concat', 'join', 'slice'], function(name) {
var method = ArrayProto[name];
_.prototype[name] = function() {
return result.call(this, method.apply(this._wrapped, arguments));
};
});