打印Javascript对象数组的有效方法？

Question

I have an Array of Objects as similar to,

var aData = [{"name":"abc","age":12},{"name":"xyz","age":20}];

All the Objects will have the same properties. Now i'll have to create a string similar to,

name age
abc 12
xyz 20

I'm able to achieve this by doing as below,

for(i=0;i<aData.length;i++){

  // Loop for printing the heading
  if(i==0){      
     for(key in aData[i]){
       outputString += key + "\t"; 
      }
     outputString += "\n";
  }

  //Lopp for printing the values 
  for(key in aData[i]){
     outputString += aData[i].key + "\t";
  }
  outputString += "\n";
}

The above implementation works fine for me, but i'm trying to find if there is an optimal way of doing this. In my case, the array size depends on the value returned by database which might be huge. I feel i'm using an additional loop as well as an if condition that would be checked for every iteration.

Answer 1

You can possibly pull the first inner loop

 for(key in aData[i]){
   outputString += key + "\t"; 
  }
 outputString += "\n";

outside the main loop. You have to check that the length of aData is not zero and if it is not then you use the first object in the array to print the headings.

Another improvement is to gather all the property names from the first object outside the main loop (so you do that only once) and use these names to access the properties of all objects thereafter.

I am not sure of the actual performance gain, but you can try it out.