在javascript中过滤数组的有效方法

Question

下面的代码需要很长时间;

var table = new Array();
for(var i =0; i< dtObjects.Rows.length; i++)
        {
            for(var j=0; j< dtColumns.Rows.length; j++)
            {
                for(var k=0; k< dtTypes.Rows.length; k++)
                {
                  if((dtObjects.Rows[i].Id == dtColumns.Rows[j].Id) && (dtColumns.Rows[j].xtype == dtTypes.Rows[k].xtype))  

                      table.push({
                          TableName : dtObjects.Rows[i].Name,
                          Type:  dtObjects.Rows[i].type,
                          ColumName:  dtColumns.Rows[j].Name,
                          DataType: dtTypes.Rows[k].Name,
                          Length : dtColumns.Rows[j].Length
                      });
                }
            }
        }

dtObjects.Rows.length = 900

dtColumns.Rows.length = 1500

dtTypes.Rows.length = 30

反正有没有在几秒钟内实现(过滤)这个？

Answer 1

如果没有任何示例数据，我们将无法做太多事情，但概括地说，这就是我看待解决方案的方式

var table = new Array();

var dtObjectMap = {}, dtColumnMap = {};
for (var i = 0; i < dtObjects.Rows.length; i++) {
    dtObjectMap['id-' + dtObjects.Rows[i].Id] = dtObjects.Rows[i];
}

for (var j = 0; j < dtColumns.Rows.length; j++) {
    if (!dtColumnMap[dtColumns.Rows[j].xtype]) {
        dtColumnMap[dtColumns.Rows[j].xtype] = [];
    }
    dtColumnMap[dtColumns.Rows[j].xtype].push(dtColumns.Rows[j]);
}

var dtObject, dtColumn, dtType, dtCXtypes;
for (var k = 0; k < dtTypes.Rows.length; k++) {
    dtType = dtType.Rows[i], dtCXtypes = dtColumnXtypes[dtType.xtype];
    if (dtCXtypes && dtCXtypes.length) {
        for (var l = 0; l < dtCXtypes.length; l++) {
            dtColumn = dtCXtypes[l];
            dtObject = dtObjectMap['id-' + dtColumn.id];
            if (dtObject) {
                table.push({
                    TableName : dtObject.Name,
                    Type : dtObject.type,
                    ColumName : dtColumn.Name,
                    DataType : dtType.Name,
                    Length : dtColumn.Length
                });
            }
        }
    }
}