Create object-properties from an array

Question

I'm writing a simple table-oriented storage for objects. The schema of a table is stored in the columns-array and the data in the rows-array.

// example: table "employees"
var columns = ["id", "name"]
var rows = [[1, "Alice"], [2, "Bob"]];

I wrote a function to convert a row-array into an object:

function convertRowToObject(row) {
 var result = {};
 for (var i = 0; i < columns.length; i++) result[columns[i]] = row[i];
 return result;
}

Now I can get an employee-object where I can access the fields by name, not by index.

// [1, "Alice"] -> { id: 1, name: "Alice" }

Is there any way to get the convertRowToObject function any smaller? I think there should be a way to get rid of the loop and make this with a single line of code.

Answer 1

You could make it smaller by turning your function into a constructor:

function RowObject(row) {
 for (var i = 0; i < columns.length; i++) 
 this[columns[i]] = row[i];
}

You would have to call this function with new then. I would avoid putting the assignment on the same line as the for, it is too Golfic to maintain.

The only way to avoid a loop is to fake it:

function convertRowToObject2(row) {
 //o -> object, v -> value, i -> index
 return row.reduce( function(o, v, i){ o[columns[i]] = v; return o; } , {} );
}

• user2033412: I like the one-liner, but the compiler will not know that he can handle the elements of the array independently, hence I will not be executed in parallel, as it can be done with map for example.