javascript實現佇列

function QueueLoadFile(deals) {

    var _self = this,
        defer = $.Deferred();

    var _queueList = [],
        _queueLen = 0,
        _isDoing = false;

    function push(deals) {
        var _self = this,
            beginIndex = _queueLen;

        if(!deals) {
            return ;
        }

        if(deals instanceof Array) {
            for(var i= 0, len=deals.length; i<len; ++i) {
                _push(deals[i]);
            }
        } else {
            _push(deals);
        }
        return beginIndex;
    }

    function _push(deal) {
        _queueList.push({
            id: deal.id,
            data: deal.data,
            action: typeof deal.action === 'function' ? deal.action : normal,
            status: 'ready',
            result: ''
        });
        _queueLen ++;
        _isDoing && _doing(_queueList.length-1);
    }

    function _doing(index) {

        if(!_queueList[index]) {
            _queueLen--;
        }

        if(_queueLen==0) {
            defer.resolve();
        }

        if(_queueList[index].status != 'finished' && _queueList[index].status != 'wrong'){
            _queueList[index].action.call(_self, _queueList[index].data).done(function(data){
                _queueList[index].result = data;
                _queueList[index].status = 'finished';
                _queueLen --;
                console.log( '[ EVENT ]  ' + (_queueList[index].id || index) + '::  ' + ('finished...') );

                (_queueLen==0) && defer.resolve(_queueList);
            }).fail(function(){
                _queueList[index].status = 'wrong';

                defer.reject(_queueList[index]);
            });
        }

        _queueList[index].status = 'doing';
    }

    function begain() {
        var _self = this;

        if(!_self._isDoing) {
            for(var len=_queueLen-1; len>=0; --len) {
                _doing(len);
            }
        }

        return defer.promise();
    }

    function normal() {
        var def = $.Deferred();
        def.resolve('');
        return def.promise();
    }

    push(deals);

    // exports
    _self.begain = begain;
    _self.push = push;
}