pId的數據結構轉children 數據結構(JS)；

在工作中經常遇到需要把帶有pId的的list數據轉換為children格式的樹形結構，一直都
沒有找到太好的工具函數。偶然間看到了這個函數，研究了下，感覺這個函數很強大，所以
記錄下來,作為備用，同時也貼出來，供大家使用;

/** 
 * json格式轉樹狀結構 
 * @param   {json}      json數據 
 * @param   {String}    id的字符串 
 * @param   {String}    父id的字符串 
 * @param   {String}    children的字符串 
 * @return  {Array}     數組 
 */  
function transData(a, idStr, pidStr, chindrenStr){  
    var r = [], hash = {}, id = idStr, pid = pidStr, children = chindrenStr, i = 0, j = 0, len = a.length;  
    for(; i < len; i++){  
        hash[a[i][id]] = a[i];  
    }  
    for(; j < len; j++){  
        var aVal = a[j], hashVP = hash[aVal[pid]];  
        if(hashVP){  
            !hashVP[children] && (hashVP[children] = []);  
            hashVP[children].push(aVal);  
        }else{  
            r.push(aVal);  
        }  
    }  
    return r;  
}  
  
var jsonData = eval('[{"id":"4","pid":"1","name":"大家電"},{"id":"5","pid":"1","name":"生活電器"},{"id":"1","pid":"0","name":"家用電器"},{"id":"2","pid":"0","name":"服飾"},{"id":"3","pid":"0","name":"化妝"},{"id":"7","pid":"4","name":"空調"},{"id":"8","pid":"4","name":"冰箱"},{"id":"9","pid":"4","name":"洗衣機"},{"id":"10","pid":"4","name":"熱水器"},{"id":"11","pid":"3","name":"面部護理"},{"id":"12","pid":"3","name":"口腔護理"},{"id":"13","pid":"2","name":"男裝"},{"id":"14","pid":"2","name":"女裝"},{"id":"15","pid":"7","name":"海爾空調"},{"id":"16","pid":"7","name":"美的空調"},{"id":"19","pid":"5","name":"加濕器"},{"id":"20","pid":"5","name":"電熨斗"}]');  
  
var jsonDataTree = transData(jsonData, 'id', 'pid', 'chindren');  
console.log(jsonDataTree);  
//[{"id":"1","pid":"0","name":"家用電器","chindren":[{"id":"4","pid":"1","name":"大家電","chindren":[{"id":"7","pid":"4","name":"空調","chindren":[{"id":"15","pid":"7","name":"海爾空調"},{"id":"16","pid":"7","name":"美的空調"}]},{"id":"8","pid":"4","name":"冰箱"},{"id":"9","pid":"4","name":"洗衣機"},{"id":"10","pid":"4","name":"熱水器"}]},{"id":"5","pid":"1","name":"生活電器","chindren":[{"id":"19","pid":"5","name":"加濕器"},{"id":"20","pid":"5","name":"電熨斗"}]}]},{"id":"2","pid":"0","name":"服飾","chindren":[{"id":"13","pid":"2","name":"男裝"},{"id":"14","pid":"2","name":"女裝"}]},{"id":"3","pid":"0","name":"化妝","chindren":[{"id":"11","pid":"3","name":"面部護理"},{"id":"12","pid":"3","name":"口腔護理"}]}]