js中实现Map
自己项目中用到了这个，记录下来，以便下次不用到处找
//***************************** Map javascript **************************function Map(linkItems) { this.current = undefined; this._size = 0; if(linkItems === false){ this.disableLinking(); } }/** * get currently map * @return current object */Map.noop = function() { return this; }; /** * invalid operation * @return */Map.illegal = function() { throw new Error('invalid operation, the Map has been disable');}; /** * * @param obj * @param foreignKeys * @return */Map.from = function(obj, foreignKeys) { var map = new Map; for(var prop in obj) { if(foreignKeys || obj.hasOwnProperty(prop)){ map.put(prop, obj[prop]); } } return map; }; /** * disable map * @return */Map.prototype.disableLinking = function() { this.link = Map.noop; this.unlink = Map.noop; this.disableLinking = Map.noop; this.next = Map.illegal; this.key = Map.illegal; this.value = Map.illegal; this.clear = Map.illegal; return this; }; /** * return hash value eg: number 123 * @param value key/value * @return */Map.prototype.hash = function(value) { return (typeof value) + ' ' + (value instanceof Object ? (value.__hash || (value.__hash = ++arguments.callee.current)) : value.toString()); }; /** * return map length * @return */Map.prototype.size = function() { return this._size;}; Map.prototype.hash.current = 0; /** * get value by key * @param key * @return */Map.prototype.get = function(key) { var item = this[this.hash(key)]; return item === undefined ? undefined : item.value; }; /** * push the value into map * @param key * @param value * @return */Map.prototype.put = function(key, value) { var hash = this.hash(key); if(this[hash] === undefined) { var item = { key : key, value : value }; this[hash] = item; this.link(item); ++this._size; }else{ this[hash].value = value; } return this; }; /** * delete value by key * @param key * @return */Map.prototype.remove = function(key) { var hash = this.hash(key); var item = this[hash]; if(item !== undefined) { --this._size; this.unlink(item); delete this[hash]; } return this; }; /** * clear map * @return */Map.prototype.clear = function() { while(this._size){this.remove(this.key()); } return this; }; /** * queue * @param item * @return */Map.prototype.link = function(item) { if(this._size == 0) { item.prev = item; item.next = item; this.current = item; }else { item.prev = this.current.prev; item.prev.next = item; item.next = this.current; this.current.prev = item; } }; Map.prototype.unlink = function(item) { if(this._size == 0){ this.current = undefined; }else { item.prev.next = item.next; item.next.prev = item.prev; if(item === this.current){ this.current = item.next; } } }; /** * get next * @return */Map.prototype.next = function() { this.current = this.current.next; return this;}; /** * get current key * @return */Map.prototype.key = function() { return this.current.key; }; /** * get current value * @return */Map.prototype.value = function() { return this.current.value; }; //***************************** Map javascript **************************